code: def symmetrize(self, method=None, copy=False):
      '''Symmetrizes (ignores method). Returns a copy if copy=True.'''
      if copy:
        return SymmEdgePairGraph(self._pairs.copy(),
                                 num_vertices=self._num_vertices)
      shape = (self._num_vertices, self._num_vertices)
      flat_inds = np.union1d(np.ravel_multi_index(self._pairs.T, shape),
                             np.ravel_multi_index(self._pairs.T[::-1], shape))
      self._pairs = np.transpose(np.unravel_index(flat_inds, shape))
      return self symmetrize(self, method=None, copy=False):
      '''Symmetrizes (ignores method). Returns a copy if copy=True.'''
      if copy:
        return SymmEdgePairGraph(self._pairs.copy(),
                                 num_vertices=self._num_vertices)
      shape = (self._num_vertices, self._num_vertices)
      flat_inds = np.union1d(np.ravel_multi_index(self._pairs.T, shape),
                             np.ravel_multi_index(self._pairs.T[::-1], shape))
      self._pairs = np.transpose(np.unravel_index(flat_inds, shape))
      return self
docs: Symmetrizes (ignores method). Returns a copy if copy=True.