code: func (f Format) MediaType() string {
  	switch f {
  	case FormatJSONPB:
  		return mtPRPCJSONPB
  	case FormatText:
  		return mtPRPCText
  	case FormatBinary:
  		fallthrough
  	default:
  		return mtPRPCBinary
  	}
  }
docs: // MediaType returns a full media type for f.