big updates: tests, bug fixed, documentation. oh my

encoding/coder.go

@@ -1,6 +1,10 @@
+// Package encoding provides generic encoder and decoder function types.
 package encoding
 
 import "io"
 
+// Encoder is a function that encodes data to a writer.
 type Encoder func(io.Writer, interface{}) error
+
+// Decoder is a function that decodes data from a reader.
 type Decoder func(io.Reader, interface{}) error