def distance(x_0, y_0, x_1, y_1):
    """Return distance between 2 points (x_0, y_0) and (x_1, y_1)
    """    
    x_dist = x_0 - x_1
    y_dist = y_0 - y_1

    return(x_dist ** 2 + y_dist ** 2) ** 0.5