Make deserializer interface private

I'd like to avoid people using this for the time being.

Author: oschwald

decoder.go

@@ -56,7 +56,7 @@ func (d *decoder) decode(offset uint, result reflect.Value, depth int) (uint, er
 	return d.decodeFromType(typeNum, size, newOffset, result, depth+1)
 }
 
-func (d *decoder) decodeToDeserializer(offset uint, dser Deserializer, depth int) (uint, error) {
+func (d *decoder) decodeToDeserializer(offset uint, dser deserializer, depth int) (uint, error) {
 	if depth > maximumDataStructureDepth {
 		return 0, newInvalidDatabaseError("exceeded maximum data structure depth; database is likely corrupt")
 	}
@@ -173,7 +173,7 @@ func (d *decoder) decodeFromTypeToDeserializer(
 	dtype dataType,
 	size uint,
 	offset uint,
-	dser Deserializer,
+	dser deserializer,
 	depth int,
 ) (uint, error) {
 	// For these types, size has a special meaning
@@ -564,7 +564,7 @@ func (d *decoder) decodeMap(
 func (d *decoder) decodeMapToDeserializer(
 	size uint,
 	offset uint,
-	dser Deserializer,
+	dser deserializer,
 	depth int,
 ) (uint, error) {
 	err := dser.StartMap(size)
@@ -645,7 +645,7 @@ func (d *decoder) decodeSlice(
 func (d *decoder) decodeSliceToDeserializer(
 	size uint,
 	offset uint,
-	dser Deserializer,
+	dser deserializer,
 	depth int,
 ) (uint, error) {
 	err := dser.StartSlice(size)

deserializer.go

@@ -2,7 +2,7 @@ package maxminddb
 
 import "math/big"
 
-// Deserializer is an interface for a type that deserializes an MaxMind DB
+// deserializer is an interface for a type that deserializes an MaxMind DB
 // data record to some other type. This exists as an alternative to the
 // standard reflection API.
 //
@@ -13,7 +13,7 @@ import "math/big"
 // This interface and the associated unmarshaling code is EXPERIMENTAL!
 // It is not currently covered by any Semantic Versioning guarantees.
 // Use at your own risk.
-type Deserializer interface {
+type deserializer interface {
 	StartSlice(uint) error
 	StartMap(uint) error
 	End() error

reader.go

@@ -227,7 +227,7 @@ func (r *Reader) decode(offset uintptr, result interface{}) error {
 		return errors.New("result param must be a pointer")
 	}
 
-	if dser, ok := result.(Deserializer); ok {
+	if dser, ok := result.(deserializer); ok {
 		_, err := r.decoder.decodeToDeserializer(uint(offset), dser, 0)
 		return err
 	}