def _find_in_list(key, a, start=None, force=False):
    """key - object you want to find
    a - list to search
    return - index in a
    """
    if start is None:
        sequence = range(0, len(a))
    else:
        sequence = range(start, len(a))
    for i in sequence:
        if a[i] == key:
            return i
    assert not force, '%s not found' % key