def _is_fix_comment(line, isstrict):
    """
    Check whether line is a comment line in fixed format Fortran source.

    :param str line: Line of code to check
    :param bool isstrict: Whether we are strictly enforcing fixed/free fmt

    References
    ----------
    :f2008:`3.3.3`
    """
    if line:
        if line[0] in '*cC!':
            return True
        if not isstrict:
            i = line.find('!')
            if i != -1:
                start = line[:i].lstrip()
                if not start:
                    if i == 5:
                        return False
                    return True
                else:
                    pass
    elif line == '':
        return True
    return False
