code: def find_kwarg(self, request, names, required, default, kwargs):
          
          val = default
          found_name = ''
          for name in names:
              if name in kwargs:
                  val = kwargs[name]
                  found_name = name
                  break
  
          if not found_name and required:
              raise ValueError("required param {} does not exist".format(self.name))
  
          return found_name, val
docs: actually try to retrieve names key from params dict
  
          :param request: the current request instance, handy for child classes
          :param names: the names this kwarg can be
          :param required: True if a name has to be found in kwargs
          :param default: the default value if name isn't found
          :param kwargs: the kwargs that will be used to find the value
          :returns: tuple, found_name, val where found_name is the actual name kwargs contained