diff --git a/merkle/db.go b/merkle/db.go
index 89f3c05cb..74c180a3a 100644
--- a/merkle/db.go
+++ b/merkle/db.go
@@ -22,13 +22,13 @@ func NewLDBDatabase(name string) (*LDBDatabase, error) {
 
 func (db *LDBDatabase) Put(key []byte, value []byte) {
 	err := db.db.Put(key, value, nil)
-	if err != nil {
-		fmt.Println("Error put", err)
-	}
+	if err != nil { panic(err) }
 }
 
-func (db *LDBDatabase) Get(key []byte) ([]byte, error) {
-	return db.db.Get(key, nil)
+func (db *LDBDatabase) Get(key []byte) ([]byte) {
+	res, err := db.db.Get(key, nil)
+    if err != nil { panic(err) }
+    return res
 }
 
 func (db *LDBDatabase) Delete(key []byte) error {
diff --git a/merkle/iavl.go b/merkle/iavl.go
index 6b6ebde46..46ab71b63 100644
--- a/merkle/iavl.go
+++ b/merkle/iavl.go
@@ -1,12 +1,11 @@
 package merkle
 
 import (
-    "bytes"
-    "math"
-    "io"
     "crypto/sha256"
 )
 
+const HASH_BYTE_SIZE int = 4+32
+
 // Immutable AVL Tree (wraps the Node root)
 
 type IAVLTree struct {
@@ -33,16 +32,15 @@ func (self *IAVLTree) Has(key Key) bool {
     return self.root.Has(nil, key)
 }
 
-func (self *IAVLTree) Put(key Key, value Value) (err error) {
+func (self *IAVLTree) Put(key Key, value Value) {
     self.root, _ = self.root.Put(nil, key, value)
-    return nil
 }
 
-func (self *IAVLTree) Hash() ([]byte, uint64) {
+func (self *IAVLTree) Hash() (ByteSlice, uint64) {
     return self.root.Hash()
 }
 
-func (self *IAVLTree) Get(key Key) (value Value, err error) {
+func (self *IAVLTree) Get(key Key) (value Value) {
     return self.root.Get(nil, key)
 }
 
@@ -104,27 +102,18 @@ func (self *IAVLNode) Right(db Db) Node {
     return self.right_filled(db)
 }
 
-func (self *IAVLNode) left_filled(db Db) *IAVLNode {
-    // XXX
-    return self.left
-}
-
-func (self *IAVLNode) right_filled(db Db) *IAVLNode {
-    // XXX
-    return self.right
-}
-
 func (self *IAVLNode) Size() uint64 {
-    if self == nil {
-        return 0
-    }
+    if self == nil { return 0 }
     return self.size
 }
 
+func (self *IAVLNode) Height() uint8 {
+    if self == nil { return 0 }
+    return self.height
+}
+
 func (self *IAVLNode) Has(db Db, key Key) (has bool) {
-    if self == nil {
-        return false
-    }
+    if self == nil { return false }
     if self.key.Equals(key) {
         return true
     } else if key.Less(self.key) {
@@ -134,12 +123,10 @@ func (self *IAVLNode) Has(db Db, key Key) (has bool) {
     }
 }
 
-func (self *IAVLNode) Get(db Db, key Key) (value Value, err error) {
-    if self == nil {
-        return nil, NotFound(key)
-    }
+func (self *IAVLNode) Get(db Db, key Key) (value Value) {
+    if self == nil { return nil }
     if self.key.Equals(key) {
-        return self.value, nil
+        return self.value
     } else if key.Less(self.key) {
         return self.left_filled(db).Get(db, key)
     } else {
@@ -147,78 +134,177 @@ func (self *IAVLNode) Get(db Db, key Key) (value Value, err error) {
     }
 }
 
-func (self *IAVLNode) Bytes() []byte {
-    b := new(bytes.Buffer)
-    self.WriteTo(b)
-    return b.Bytes()
-}
-
-func (self *IAVLNode) Hash() ([]byte, uint64) {
-    if self == nil {
-        return nil, 0
-    }
+func (self *IAVLNode) Hash() (ByteSlice, uint64) {
+    if self == nil { return nil, 0 }
     if self.hash != nil {
         return self.hash, 0
     }
 
+    size := self.ByteSize()
+    buf := make([]byte, size, size)
     hasher := sha256.New()
-    _, hashCount, err := self.WriteTo(hasher)
-    if err != nil { panic(err) }
+    _, hashCount := self.saveToCountHashes(buf)
+    hasher.Write(buf)
     self.hash = hasher.Sum(nil)
 
-    return self.hash, hashCount
+    return self.hash, hashCount+1
+}
+
+// TODO: don't clear the hash if the value hasn't changed.
+func (self *IAVLNode) Put(db Db, key Key, value Value) (_ *IAVLNode, updated bool) {
+    if self == nil {
+        return &IAVLNode{key: key, value: value, height: 1, size: 1, hash: nil}, false
+    }
+
+    self = self.Copy()
+
+    if self.key.Equals(key) {
+        self.value = value
+        return self, true
+    }
+
+    if key.Less(self.key) {
+        self.left, updated = self.left_filled(db).Put(db, key, value)
+    } else {
+        self.right, updated = self.right_filled(db).Put(db, key, value)
+    }
+    if updated {
+        return self, updated
+    } else {
+        self.calc_height_and_size(db)
+        return self.balance(db), updated
+    }
 }
 
-func (self *IAVLNode) WriteTo(writer io.Writer) (written int64, hashCount uint64, err error) {
+func (self *IAVLNode) Remove(db Db, key Key) (new_self *IAVLNode, value Value, err error) {
+    if self == nil { return nil, nil, NotFound(key) }
 
-    write := func(bytes []byte) {
-        if err == nil {
-            var n int
-            n, err = writer.Write(bytes)
-            written += int64(n)
+    if self.key.Equals(key) {
+        if self.left != nil && self.right != nil {
+            if self.left_filled(db).Size() < self.right_filled(db).Size() {
+                self, new_self = self.pop_node(db, self.right_filled(db).lmd(db))
+            } else {
+                self, new_self = self.pop_node(db, self.left_filled(db).rmd(db))
+            }
+            new_self.left = self.left
+            new_self.right = self.right
+            new_self.calc_height_and_size(db)
+            return new_self, self.value, nil
+        } else if self.left == nil {
+            return self.right_filled(db), self.value, nil
+        } else if self.right == nil {
+            return self.left_filled(db), self.value, nil
+        } else {
+            return nil, self.value, nil
         }
     }
 
+    if key.Less(self.key) {
+        if self.left == nil {
+            return self, nil, NotFound(key)
+        }
+        var new_left *IAVLNode
+        new_left, value, err = self.left_filled(db).Remove(db, key)
+        if new_left == self.left_filled(db) { // not found
+            return self, nil, err
+        } else if err != nil { // some other error
+            return self, value, err
+        }
+        self = self.Copy()
+        self.left = new_left
+    } else {
+        if self.right == nil {
+            return self, nil, NotFound(key)
+        }
+        var new_right *IAVLNode
+        new_right, value, err = self.right_filled(db).Remove(db, key)
+        if new_right == self.right_filled(db) { // not found
+            return self, nil, err
+        } else if err != nil { // some other error
+            return self, value, err
+        }
+        self = self.Copy()
+        self.right = new_right
+    }
+    self.calc_height_and_size(db)
+    return self.balance(db), value, err
+}
+
+func (self *IAVLNode) ByteSize() int {
+    // 1 byte node descriptor
+    // 1 byte node neight
+    // 8 bytes node size
+    size := 10
+    size += self.key.ByteSize()
+    if self.value != nil {
+        size += self.value.ByteSize()
+    } else {
+        size += 1
+    }
+    if self.left != nil {
+        size += HASH_BYTE_SIZE
+    }
+    if self.right != nil {
+        size += HASH_BYTE_SIZE
+    }
+    return size
+}
+
+func (self *IAVLNode) SaveTo(buf []byte) int {
+    written, _ := self.saveToCountHashes(buf)
+    return written
+}
+
+func (self *IAVLNode) saveToCountHashes(buf []byte) (int, uint64) {
+    cur := 0
+    hashCount := uint64(0)
+
     // node descriptor
     nodeDesc := byte(0)
     if self.value != nil { nodeDesc |= 0x01 }
     if self.left != nil  { nodeDesc |= 0x02 }
     if self.right != nil { nodeDesc |= 0x04 }
-    write([]byte{nodeDesc})
+    cur += UInt8(nodeDesc).SaveTo(buf[cur:])
 
     // node height & size
-    write(UInt8(self.height).Bytes())
-    write(UInt64(self.size).Bytes())
+    cur += UInt8(self.height).SaveTo(buf[cur:])
+    cur += UInt64(self.size).SaveTo(buf[cur:])
 
     // node key
-    keyBytes := self.key.Bytes()
-    if len(keyBytes) > 255 { panic("key is too long") }
-    write([]byte{byte(len(keyBytes))})
-    write(keyBytes)
+    cur += self.key.SaveTo(buf[cur:])
 
     // node value
     if self.value != nil {
-        valueBytes := self.value.Bytes()
-        if len(valueBytes) > math.MaxUint32 { panic("value is too long") }
-        write([]byte{byte(len(valueBytes))})
-        write(valueBytes)
+        cur += self.value.SaveTo(buf[cur:])
+    } else {
+        cur += UInt8(0).SaveTo(buf[cur:])
     }
 
     // left child
     if self.left != nil {
         leftHash, leftCount := self.left.Hash()
         hashCount += leftCount
-        write(leftHash)
+        cur += leftHash.SaveTo(buf[cur:])
     }
 
     // right child
     if self.right != nil {
         rightHash, rightCount := self.right.Hash()
         hashCount += rightCount
-        write(rightHash)
+        cur += rightHash.SaveTo(buf[cur:])
     }
 
-    return written, hashCount+1, err
+    return cur, hashCount
+}
+
+func (self *IAVLNode) left_filled(db Db) *IAVLNode {
+    // XXX
+    return self.left
+}
+
+func (self *IAVLNode) right_filled(db Db) *IAVLNode {
+    // XXX
+    return self.right
 }
 
 // Returns a new tree (unless node is the root) & a copy of the popped node.
@@ -332,97 +418,6 @@ func (self *IAVLNode) balance(db Db) (new_self *IAVLNode) {
     return self
 }
 
-// TODO: don't clear the hash if the value hasn't changed.
-func (self *IAVLNode) Put(db Db, key Key, value Value) (_ *IAVLNode, updated bool) {
-    if self == nil {
-        return &IAVLNode{key: key, value: value, height: 1, size: 1, hash: nil}, false
-    }
-
-    self = self.Copy()
-
-    if self.key.Equals(key) {
-        self.value = value
-        return self, true
-    }
-
-    if key.Less(self.key) {
-        self.left, updated = self.left_filled(db).Put(db, key, value)
-    } else {
-        self.right, updated = self.right_filled(db).Put(db, key, value)
-    }
-    if updated {
-        return self, updated
-    } else {
-        self.calc_height_and_size(db)
-        return self.balance(db), updated
-    }
-}
-
-func (self *IAVLNode) Remove(db Db, key Key) (new_self *IAVLNode, value Value, err error) {
-    if self == nil {
-        return nil, nil, NotFound(key)
-    }
-
-    if self.key.Equals(key) {
-        if self.left != nil && self.right != nil {
-            if self.left_filled(db).Size() < self.right_filled(db).Size() {
-                self, new_self = self.pop_node(db, self.right_filled(db).lmd(db))
-            } else {
-                self, new_self = self.pop_node(db, self.left_filled(db).rmd(db))
-            }
-            new_self.left = self.left
-            new_self.right = self.right
-            new_self.calc_height_and_size(db)
-            return new_self, self.value, nil
-        } else if self.left == nil {
-            return self.right_filled(db), self.value, nil
-        } else if self.right == nil {
-            return self.left_filled(db), self.value, nil
-        } else {
-            return nil, self.value, nil
-        }
-    }
-
-    if key.Less(self.key) {
-        if self.left == nil {
-            return self, nil, NotFound(key)
-        }
-        var new_left *IAVLNode
-        new_left, value, err = self.left_filled(db).Remove(db, key)
-        if new_left == self.left_filled(db) { // not found
-            return self, nil, err
-        } else if err != nil { // some other error
-            return self, value, err
-        }
-        self = self.Copy()
-        self.left = new_left
-    } else {
-        if self.right == nil {
-            return self, nil, NotFound(key)
-        }
-        var new_right *IAVLNode
-        new_right, value, err = self.right_filled(db).Remove(db, key)
-        if new_right == self.right_filled(db) { // not found
-            return self, nil, err
-        } else if err != nil { // some other error
-            return self, value, err
-        }
-        self = self.Copy()
-        self.right = new_right
-    }
-    self.calc_height_and_size(db)
-    return self.balance(db), value, err
-}
-
-func (self *IAVLNode) Height() uint8 {
-    if self == nil {
-        return 0
-    }
-    return self.height
-}
-
-// ...
-
 func (self *IAVLNode) _md(side func(*IAVLNode)*IAVLNode) (*IAVLNode) {
     if self == nil {
         return nil
diff --git a/merkle/iavl_test.go b/merkle/iavl_test.go
index 295c1f17c..ec0d2c368 100644
--- a/merkle/iavl_test.go
+++ b/merkle/iavl_test.go
@@ -80,9 +80,7 @@ func TestImmutableAvlPutHasGetRemove(t *testing.T) {
         if has := tree.Has(nil, randstr(12)); has {
             t.Error("Table has extra key")
         }
-        if val, err := tree.Get(nil, r.key); err != nil {
-            t.Error(err, val.(String), r.value)
-        } else if !(val.(String)).Equals(r.value) {
+        if val := tree.Get(nil, r.key); !(val.(String)).Equals(r.value) {
             t.Error("wrong value")
         }
     }
@@ -100,9 +98,7 @@ func TestImmutableAvlPutHasGetRemove(t *testing.T) {
             if has := tree.Has(nil, randstr(12)); has {
                 t.Error("Table has extra key")
             }
-            if val, err := tree.Get(nil, r.key); err != nil {
-                t.Error(err)
-            } else if !(val.(String)).Equals(r.value) {
+            if val := tree.Get(nil, r.key); !(val.(String)).Equals(r.value) {
                 t.Error("wrong value")
             }
         }
@@ -151,9 +147,7 @@ func TestTraversals(t *testing.T) {
     test := func(T Tree) {
         t.Logf("%T", T)
         for j := range order {
-            if err := T.Put(Int(data[order[j]]), Int(order[j])); err != nil {
-                t.Error(err)
-            }
+            T.Put(Int(data[order[j]]), Int(order[j]))
         }
 
         j := 0
diff --git a/merkle/int.go b/merkle/int.go
index f16022e87..d6d6a09a7 100644
--- a/merkle/int.go
+++ b/merkle/int.go
@@ -16,6 +16,8 @@ type Int int
 type UInt uint
 
 
+// Int8
+
 func (self Int8) Equals(other Key) bool {
     if o, ok := other.(Int8); ok {
         return self == o
@@ -32,10 +34,22 @@ func (self Int8) Less(other Key) bool {
     }
 }
 
-func (self Int8) Bytes() []byte {
-    return []byte{byte(self)}
+func (self Int8) ByteSize() int {
+    return 1
+}
+
+func (self Int8) SaveTo(b []byte) int {
+    if cap(b) < 1 { panic("buf too small") }
+    b[0] = byte(self)
+    return 1
 }
 
+func LoadInt8(bytes []byte) Int8 {
+    return Int8(bytes[0])
+}
+
+
+// UInt8
 
 func (self UInt8) Equals(other Key) bool {
     if o, ok := other.(UInt8); ok {
@@ -53,10 +67,22 @@ func (self UInt8) Less(other Key) bool {
     }
 }
 
-func (self UInt8) Bytes() []byte {
-    return []byte{byte(self)}
+func (self UInt8) ByteSize() int {
+    return 1
 }
 
+func (self UInt8) SaveTo(b []byte) int {
+    if cap(b) < 1 { panic("buf too small") }
+    b[0] = byte(self)
+    return 1
+}
+
+func LoadUInt8(bytes []byte) UInt8 {
+    return UInt8(bytes[0])
+}
+
+
+// Int16
 
 func (self Int16) Equals(other Key) bool {
     if o, ok := other.(Int16); ok {
@@ -74,12 +100,22 @@ func (self Int16) Less(other Key) bool {
     }
 }
 
-func (self Int16) Bytes() []byte {
-    b := [2]byte{}
-    binary.LittleEndian.PutUint16(b[:], uint16(self))
-    return b[:]
+func (self Int16) ByteSize() int {
+    return 2
 }
 
+func (self Int16) SaveTo(b []byte) int {
+    if cap(b) < 2 { panic("buf too small") }
+    binary.LittleEndian.PutUint16(b, uint16(self))
+    return 2
+}
+
+func LoadInt16(bytes []byte) Int16 {
+    return Int16(binary.LittleEndian.Uint16(bytes))
+}
+
+
+// UInt16
 
 func (self UInt16) Equals(other Key) bool {
     if o, ok := other.(UInt16); ok {
@@ -97,13 +133,23 @@ func (self UInt16) Less(other Key) bool {
     }
 }
 
-func (self UInt16) Bytes() []byte {
-    b := [2]byte{}
-    binary.LittleEndian.PutUint16(b[:], uint16(self))
-    return b[:]
+func (self UInt16) ByteSize() int {
+    return 2
+}
+
+func (self UInt16) SaveTo(b []byte) int {
+    if cap(b) < 2 { panic("buf too small") }
+    binary.LittleEndian.PutUint16(b, uint16(self))
+    return 2
+}
+
+func LoadUInt16(bytes []byte) UInt16 {
+    return UInt16(binary.LittleEndian.Uint16(bytes))
 }
 
 
+// Int32
+
 func (self Int32) Equals(other Key) bool {
     if o, ok := other.(Int32); ok {
         return self == o
@@ -120,13 +166,23 @@ func (self Int32) Less(other Key) bool {
     }
 }
 
-func (self Int32) Bytes() []byte {
-    b := [4]byte{}
-    binary.LittleEndian.PutUint32(b[:], uint32(self))
-    return b[:]
+func (self Int32) ByteSize() int {
+    return 4
+}
+
+func (self Int32) SaveTo(b []byte) int {
+    if cap(b) < 4 { panic("buf too small") }
+    binary.LittleEndian.PutUint32(b, uint32(self))
+    return 4
+}
+
+func LoadInt32(bytes []byte) Int32 {
+    return Int32(binary.LittleEndian.Uint32(bytes))
 }
 
 
+// UInt32
+
 func (self UInt32) Equals(other Key) bool {
     if o, ok := other.(UInt32); ok {
         return self == o
@@ -143,12 +199,22 @@ func (self UInt32) Less(other Key) bool {
     }
 }
 
-func (self UInt32) Bytes() []byte {
-    b := [4]byte{}
-    binary.LittleEndian.PutUint32(b[:], uint32(self))
-    return b[:]
+func (self UInt32) ByteSize() int {
+    return 4
+}
+
+func (self UInt32) SaveTo(b []byte) int {
+    if cap(b) < 4 { panic("buf too small") }
+    binary.LittleEndian.PutUint32(b, uint32(self))
+    return 4
 }
 
+func LoadUInt32(bytes []byte) UInt32 {
+    return UInt32(binary.LittleEndian.Uint32(bytes))
+}
+
+
+// Int64
 
 func (self Int64) Equals(other Key) bool {
     if o, ok := other.(Int64); ok {
@@ -166,12 +232,22 @@ func (self Int64) Less(other Key) bool {
     }
 }
 
-func (self Int64) Bytes() []byte {
-    b := [8]byte{}
-    binary.LittleEndian.PutUint64(b[:], uint64(self))
-    return b[:]
+func (self Int64) ByteSize() int {
+    return 8
 }
 
+func (self Int64) SaveTo(b []byte) int {
+    if cap(b) < 8 { panic("buf too small") }
+    binary.LittleEndian.PutUint64(b, uint64(self))
+    return 8
+}
+
+func LoadInt64(bytes []byte) Int64 {
+    return Int64(binary.LittleEndian.Uint64(bytes))
+}
+
+
+// UInt64
 
 func (self UInt64) Equals(other Key) bool {
     if o, ok := other.(UInt64); ok {
@@ -189,13 +265,23 @@ func (self UInt64) Less(other Key) bool {
     }
 }
 
-func (self UInt64) Bytes() []byte {
-    b := [8]byte{}
-    binary.LittleEndian.PutUint64(b[:], uint64(self))
-    return b[:]
+func (self UInt64) ByteSize() int {
+    return 8
+}
+
+func (self UInt64) SaveTo(b []byte) int {
+    if cap(b) < 8 { panic("buf too small") }
+    binary.LittleEndian.PutUint64(b, uint64(self))
+    return 8
+}
+
+func LoadUInt64(bytes []byte) UInt64 {
+    return UInt64(binary.LittleEndian.Uint64(bytes))
 }
 
 
+// Int
+
 func (self Int) Equals(other Key) bool {
     if o, ok := other.(Int); ok {
         return self == o
@@ -212,12 +298,21 @@ func (self Int) Less(other Key) bool {
     }
 }
 
-func (self Int) Bytes() []byte {
-    b := [8]byte{}
-    binary.LittleEndian.PutUint64(b[:], uint64(self))
-    return b[:]
+func (self Int) ByteSize() int {
+    return 8
+}
+
+func (self Int) SaveTo(b []byte) int {
+    if cap(b) < 8 { panic("buf too small") }
+    binary.LittleEndian.PutUint64(b, uint64(self))
+    return 8
 }
 
+func LoadInt(bytes []byte) Int {
+    return Int(binary.LittleEndian.Uint64(bytes))
+}
+
+// UInt
 
 func (self UInt) Equals(other Key) bool {
     if o, ok := other.(UInt); ok {
@@ -235,8 +330,16 @@ func (self UInt) Less(other Key) bool {
     }
 }
 
-func (self UInt) Bytes() []byte {
-    b := [8]byte{}
-    binary.LittleEndian.PutUint64(b[:], uint64(self))
-    return b[:]
+func (self UInt) ByteSize() int {
+    return 8
+}
+
+func (self UInt) SaveTo(b []byte) int {
+    if cap(b) < 8 { panic("buf too small") }
+    binary.LittleEndian.PutUint64(b, uint64(self))
+    return 8
+}
+
+func LoadUInt(bytes []byte) UInt {
+    return UInt(binary.LittleEndian.Uint64(bytes))
 }
diff --git a/merkle/string.go b/merkle/string.go
index b09ab4a19..e52cc59f9 100644
--- a/merkle/string.go
+++ b/merkle/string.go
@@ -5,6 +5,8 @@ import "bytes"
 type String string
 type ByteSlice []byte
 
+// String
+
 func (self String) Equals(other Key) bool {
     if o, ok := other.(String); ok {
         return self == o
@@ -21,10 +23,25 @@ func (self String) Less(other Key) bool {
     }
 }
 
-func (self String) Bytes() []byte {
-    return []byte(self)
+func (self String) ByteSize() int {
+    return len(self)+4
+}
+
+func (self String) SaveTo(buf []byte) int {
+    if len(buf) < self.ByteSize() { panic("buf too small") }
+    UInt32(len(self)).SaveTo(buf)
+    copy(buf[4:], []byte(self))
+    return len(self)+4
 }
 
+func LoadString(bytes []byte) String {
+    length := LoadUInt32(bytes)
+    return String(bytes[4:4+length])
+}
+
+
+// ByteSlice
+
 func (self ByteSlice) Equals(other Key) bool {
     if o, ok := other.(ByteSlice); ok {
         return bytes.Equal(self, o)
@@ -41,6 +58,18 @@ func (self ByteSlice) Less(other Key) bool {
     }
 }
 
-func (self ByteSlice) Bytes() []byte {
-    return []byte(self)
+func (self ByteSlice) ByteSize() int {
+    return len(self)+4
+}
+
+func (self ByteSlice) SaveTo(buf []byte) int {
+    if len(buf) < self.ByteSize() { panic("buf too small") }
+    UInt32(len(self)).SaveTo(buf)
+    copy(buf[4:], self)
+    return len(self)+4
+}
+
+func LoadByteSlice(bytes []byte) ByteSlice {
+    length := LoadUInt32(bytes)
+    return ByteSlice(bytes[4:4+length])
 }
diff --git a/merkle/types.go b/merkle/types.go
index ecd1b0ca0..00ffdff18 100644
--- a/merkle/types.go
+++ b/merkle/types.go
@@ -4,14 +4,20 @@ import (
     "fmt"
 )
 
+type Binary interface {
+    ByteSize()      int
+    SaveTo([]byte)  int
+}
+
 type Value interface {
-    Bytes()         []byte
+    Binary
 }
 
 type Key interface {
+    Binary
+
     Equals(b Key)   bool
     Less(b Key)     bool
-    Bytes()         []byte
 }
 
 type Tree interface {
@@ -20,19 +26,21 @@ type Tree interface {
     Size()          uint64
     Height()        uint8
     Has(key Key)    bool
-    Get(key Key)    (Value, error)
-    Hash()          ([]byte, uint64)
+    Get(key Key)    Value
+    Hash()          (ByteSlice, uint64)
 
-    Put(Key, Value) (err error)
+    Put(Key, Value)
     Remove(Key)     (Value, error)
 }
 
 type Db interface {
-    Get([]byte) ([]byte, error)
-    Put([]byte, []byte) error
+    Get([]byte) []byte
+    Put([]byte, []byte)
 }
 
 type Node interface {
+    Binary
+
     Key()           Key
     Value()         Value
     Left(Db)        Node
@@ -41,9 +49,8 @@ type Node interface {
     Size()          uint64
     Height()        uint8
     Has(Db, Key)    bool
-    Get(Db, Key)    (Value, error)
-    Hash()          ([]byte, uint64)
-    Bytes()         []byte
+    Get(Db, Key)    Value
+    Hash()          (ByteSlice, uint64)
 
     Put(Db, Key, Value) (*IAVLNode, bool)
     Remove(Db, Key) (*IAVLNode, Value, error)