def index_of(items, value, key):
    """
    Return the index of the list where a value is found for the specified key.
        Parameters
    ----------
    items : the list.

    value : the value.

    key : the key.

        Return the list index where the value is found for the specified key,
    otherwise None is returned.
    """
    try:
        return [i[key] for i in items].index(value)
    except ValueError:
        return None