code: func NewInt24FieldDescriptor(nullable NullableColumn) FieldDescriptor {
  	return newFixedLengthFieldDescriptor(
  		mysql_proto.FieldType_INT24,
  		nullable,
  		3,
  		func(b []byte) interface{} { return uint64(LittleEndian.Uint24(b)) })
  }
docs: // This returns a field descriptor for FieldType_INT24 (i.e., Field_medium)