def calc_t_int(n_group, t_frame, n_frame, n_skip):
    """Calculates the integration time.
    
    Parameters
    ----------
    n_group : int
        Groups per integration.
    t_frame : float
        Frame time (in seconds).
    n_frame : int
        Frames per group -- always 1 except maybe brown dwarves.
    n_skip : int 
        Skips per integration -- always 0 except maybe brown dwarves.

    Returns
    -------
    t_int : float
        Integration time (in seconds). 
    """
    t_int = (n_group * (n_frame + n_skip) - n_skip) * t_frame
    return t_int
