code: function (input, encoding) {
          var module = _gpfEncodings[encoding];
          if (undefined === module) {
              gpf.Error.encodingNotSupported();
          }
          return new EncoderStream(module[0], input);
      }
docs: Create a encoder to convert an input text stream into an output
  binary buffer.
  
  @param {gpf.interfaces.IReadableStream} input
  @param {String} encoding
  @return {gpf.interfaces.IReadableStream}