code: def is_port_default(self):
          '''Return whether the URL is using the default port.'''
          if self.scheme in RELATIVE_SCHEME_DEFAULT_PORTS:
              return RELATIVE_SCHEME_DEFAULT_PORTS[self.scheme] == self.porf is_port_default(self):
          '''Return whether the URL is using the default port.'''
          if self.scheme in RELATIVE_SCHEME_DEFAULT_PORTS:
              return RELATIVE_SCHEME_DEFAULT_PORTS[self.scheme] == self.port
docs: Return whether the URL is using the default port.