def param(name)
      param = self.class.params[name]
      raise Error, "Undefined param #{name}" unless param
      param.convert(param_before_type_cast(name))
    end
def param(name)
      param = self.class.params[name]
      raise Error, "Undefined param #{name}" unless param
      param.convert(param_before_type_cast(name))
    end
Params