code: def contour(self, level):
          
          if not isinstance(level, numbers.Number):
              raise TypeError(
                  ("'_level' must be of type 'numbers.Number' but is "
                   "'{:s}'").format(type(level)))
          vertices = self._contour_generator.create_contour(level)
          return self.formatter(level, vertices)
docs: Get contour lines at the given level.
  
          Parameters
          ----------
          level : numbers.Number
              The data level to calculate the contour lines for.
  
          Returns
          -------
          :
              The result of the :attr:`formatter` called on the contour at the
              given `level`.