def time_to_datetime(tm):

    if tm:

        if isinstance(tm, basestring):

            try:

                tm = float(tm)

            except ValueError:

                return

        return datetime.datetime.fromtimestamp(tm)

# Must match regexp in kallithea/public/js/base.js MentionsAutoComplete()

# Check char before @ - it must not look like we are in an email addresses.

MENTIONS_REGEX = re.compile(r'(?:^|(?<=[^a-zA-Z0-9]))@([a-zA-Z0-9][-_.a-zA-Z0-9]*[a-zA-Z0-9])')

def extract_mentioned_users(s):

    r"""

    Returns unique usernames from given string s that have @mention

    :param s: string to get mentions

    >>> extract_mentioned_users('@1-2.a_X,@1234 not@not @ddd@not @n @ee @ff @gg, @gg;@hh @n\n@zz,')

    ['1-2.a_X', '1234', 'ddd', 'ee', 'ff', 'gg', 'hh', 'zz']

    """

    usrs = set()