def get_stack(key, effect_set):
    """Given a list of effects from an efect_list, extract the given `key`
    value from each object and return a string joined with a pipe `|`.

    This is used for merging many similay effects as one string

        get_stack('delay', [ChorusEffect(),ChorusEffect(),])
        ".8|.8"
    """
    r = []
    for item in effect_set:
        r.append(str(getattr(item, key)))
    return '|'.join(r)