code: def _format_vector(self, vecs, form='broadcast'):
          
          if form == 'meshed':
              return np.meshgrid(*vecs, indexing='ij')
          elif form == 'vector':
              vecs = np.meshgrid(*vecs, indexing='ij')
              return np.rollaxis(np.array(np.broadcast_arrays(*vecs)),0,self.dim+1)
          elif form == 'flat':
              return vecs
          else:
              return [v[self._coord_slicers[i]] for i,v in enumerate(vecs)]
docs: Format a 3d vector field in certain ways, see `coords` for a description
          of each formatting method.