def number_of_horizontal_links(shape):
    """Number of horizontal links in a structured quad grid.

    Parameters
    ----------
    shape : tuple of int
        Shape of grid of nodes.

    Returns
    -------
    int :
        Number of horizontal links in grid.

    Examples
    --------
    >>> from landlab.components.overland_flow._links import number_of_horizontal_links
    >>> number_of_horizontal_links((3, 4))
    9
    """
    return shape[0] * (shape[1] - 1)
