def linear_y(t0, t_step, slope, y0):
    """
    A function to generate y values that satisfied to linear relationship with independent value t_list, slope, and start point of y

    Parameters:
    -----------
    t0: t0, with dependent variable as startpoint_y
    t_step: step of t
    slope: slope
    y0: startpoint of y

    Return:
    -------
    y1: array of dependent variable that satisfied linear relationship with a given slope

    Example:
    --------
    >>> y_list = linear_y(20, 1, 3, 0)
    """
    return t_step+t0, y0+t_step*slope