def len_selfies(selfies: str) -> int:
    """Computes the symbol length of a SELFIES.

    The symbol length is the number of symbols that make up the SELFIES,
    and not the length of the string itself (i.e. ``len(selfies)``).

    :param selfies: a SELFIES.
    :return: the symbol length of ``selfies``.

    :Example:

    >>> import selfies
    >>> selfies.len_selfies('[C][O][C]')
    3
    >>> selfies.len_selfies('[C][=C][F].[C]')
    5
    """

    return selfies.count("[") + selfies.count(".")