def check_is_left(name):
    """
    Checks if the name belongs to a 'left' sequence (/1).  Returns True or
    False.

    Handles both Casava formats: seq/1 and 'seq::... 1::...'
    """
    if ' ' in name:                        # handle '@name 1:rst'
        name, rest = name.split(' ', 1)
        if rest.startswith('1:'):
            return True
    elif name.endswith('/1'):              # handle name/1
        return True

    return False