def translate(x, y, dx, dy):
    """ 
    Translate (x,y) by distance (dx, dy)
    
    Arguments
    ---------
    x,y : scalar numbers or numpy vectors
    dx, dy : scalar numbers
    
    Returns
    -------
    X,Y : same type and shape as x,y
        Points (x,y) are translated to points (X,Y).
    """
    return x + dx, y + dy