code: def _call(self, x, out=None):
          
          if out is None:
              out = self.range.element()
  
          ndim = self.range.ndim
          dx = self.range.cell_sides
  
          tmp = np.empty(out.shape, out.dtype, order=out.space.default_order)
          with writable_array(out) as out_arr:
              for axis in range(ndim):
                  finite_diff(x[axis], axis=axis, dx=dx[axis],
                              method=self.method, pad_mode=self.pad_mode,
                              pad_const=self.pad_const,
                              out=tmp)
                  if axis == 0:
                      out_arr[:] = tmp
                  else:
                      out_arr += tmp
  
          return out
docs: Calculate the divergence of ``x``.