def slope(line):
    """
    Cartesian line slope, classically defined as Δy/Δx.
    
    Parameters
    ----------
    line: shapely.LineString
        The line for which to calculate slope.
    """
    x0 = line.coords[0][0]
    y0 = line.coords[0][1]
    x1 = line.coords[1][0]
    y1 = line.coords[1][1]
    return (y1 - y0) / (x1 - x0)