def at_multimatch_cmd(caller, matches):
    """
    Format multiple command matches to a useful error.

    Args:
        caller (Object): Calling object.
        matches (list): A list of matchtuples `(num, Command)`.

    Returns:
        formatted (str): A nicely formatted string, including
            eventual errors.

    """
    string = "There were multiple matches:"
    for num, match in enumerate(matches):
        # each match is a tuple (candidate, cmd)
        cmdname, arg, cmd, dum, dum = match

        get_extra_info = cmd.get_extra_info(caller)
        string += "\n %s-%s%s" % (num + 1, cmdname, get_extra_info)
    return string