def each_field
      self.class.all_fields.each do |field|
        value = __send__(field.getter)
        yield(field, value)
      end
    end
def each_field
      self.class.all_fields.each do |field|
        value = __send__(field.getter)
        yield(field, value)
      end
    end
Iterate over every field, invoking the given block