def check_format_rules(lineno, line):
    """
    Given a line number and a line, compare them against a set of rules.  If it
    it fails a given rule, return an error message.  If it passes all rules
    then return false.
    """
    # Since enumerate starts at 0
    real_lineno = lineno + 1
    if lineno == 0:
        if len(line) > 50:
            return "E%d: First line should be less than 50 characters in " \
                    "length." % (real_lineno,)
    if lineno == 1:
        if line:
            return "E%d: Second line should be empty." % (real_lineno,)
    if not line.startswith('#'):
        if len(line) > 72:
            return "E%d: No line should be over 72 characters long." % (
                    real_lineno,)
    return False