def METHOD_NAME(self):
    """Updates gradient between each core node and its receiver.
    Used to update slope values between sub-time-steps, when we do not
    re-run flow routing.
    Examples
    --------
    >>> from landlab import RasterModelGrid
    >>> from landlab.components import FlowAccumulator
    >>> rg = RasterModelGrid((3, 4))
    >>> z = rg.add_zeros('node', 'topographic__elevation')
    >>> z[:] = rg.x_of_node + rg.y_of_node
    >>> fa = FlowAccumulator(rg, flow_director='FlowDirectorD8')
    >>> fa.run_one_step()
    >>> rg.at_node['topographic__steepest_slope'][5:7]
    array([ 1.41421356,  1.41421356])
    >>> sp = _GeneralizedErosionDeposition(rg, v_s=0.001,
    ...                                    m_sp=0.5, n_sp=1.0, F_f=0)
    >>> z *= 0.1
    >>> sp._update_flow_link_slopes()
    >>> rg.at_node['topographic__steepest_slope'][5:7]
    array([ 0.14142136,  0.14142136])
    """
    self._slope[:] = (
        self._topographic__elevation
        - self._topographic__elevation[self._flow_receivers]
    ) / self._link_lengths[self._link_to_reciever]