code: def get_self_uri(self, content_type):
          "return the first self uri with the content_type"
          try:
              return [self_uri for self_uri in self.self_uri_list
                      if self_uri.content_type == content_type][0]
          except IndexError:
              return Nonf get_self_uri(self, content_type):
          "return the first self uri with the content_type"
          try:
              return [self_uri for self_uri in self.self_uri_list
                      if self_uri.content_type == content_type][0]
          except IndexError:
              return None
docs: return the first self uri with the content_type