def sort(simulations, sortby, only_started=False, reverse=False):
    """Sort simulations by a quantity.
    Based on group.py

    Parameters
    ----------
    simulations : list
        Put here a Simulations object or a list of simulations [sim1, sim2, ...].

    sortby : string
        Put here the heyword after which the sorting shall happen.

    only_started : bool
        Only sort simulations that already has started.

    reverse : bool
        Reverse order.

    Returns
    -------
    List with simulation objects in their sorted order.
    """

    from pencil.sim import group

    def flatten(l):
        al = []
        for el in l:
            if type(el) == type(["list"]):
                al.extend(flatten(el))
            else:
                al.append(el)

        return al

    sim_dict = group(
        simulations=simulations,
        groupby=sortby,
        sort=True,
        only_started=only_started,
        reverse=reverse,
    )

    if reverse:
        return flatten(sim_dict.values())[::-1]
    else:
        return flatten(sim_dict.values())