code: func NewFloatFieldDescriptor(nullable NullableColumn, metadata []byte) (
  	fd FieldDescriptor,
  	remaining []byte,
  	err error) {
  
  	if len(metadata) < 1 {
  		return nil, nil, errors.New("metadata too short")
  	}
  
  	size := uint8(metadata[0])
  	if size != 4 {
  		return nil, nil, errors.New("invalid float size")
  	}
  
  	return newFixedLengthFieldDescriptor(
  			mysql_proto.FieldType_FLOAT,
  			nullable,
  			4,
  			func(b []byte) interface{} {
  				return float64(LittleEndian.Float32(b))
  			}),
  		metadata[1:],
  		nil
  }
docs: // This returns a field descriptor for FieldType_FLOAT (i.e., Field_float)