class ReeMapper::MapperFactory

def hash(field_name, dto: nil, **opts, &blk)
  raise ReeMapper::Error, "invalid DSL usage" unless @mapper
  type = hash_from_blk(dto: dto, &blk)
  field = ReeMapper::Field.new(type, field_name, **opts, location: caller_locations&.first&.to_s)
  @mapper.add_field(field)
end