def list_if_in(input_list, string_in):
    """Return a list without input items not containing an input string.

    Parameters
    ----------
    input_list : list[str]
        A list of strings.
    string_in : str
        A string to check items in the list.

    Returns
    -------
    list
        A copy of input list w/o strings not containing string_in.

    """
    return [string for string in input_list if string_in in string]