2020/19.py
def convert(rn) -> str:
        """
        This function converts a rule number to a regex. It uses the ``for`` loop to
        deal with the OR cases, and then joins them with "|"s. For each of the sequence
        rules, it calls itself recursively to generate a regex for the sub-rule.
        """
        parts = []
        for r in RULES[rn]:
            if isinstance(r, str):
                return r
            else:
                parts.append("".join(convert(x) for x in r))
        return "(" + "|".join(parts) + ")"

        This function converts a rule number to a regex. It uses the ``for`` loop to
        deal with the OR cases, and then joins them with "|"s. For each of the sequence
        rules, it calls itself recursively to generate a regex for the sub-rule.
        
This function converts a rule number to a regex. It uses the ``for`` loop to
deal with the OR cases, and then joins them with "|"s. For each of the sequence
rules, it calls itself recursively to generate a regex for the sub-rule.
This function converts a rule number to a regex . It uses the ` ` for ` ` loop to deal with the OR cases and then joins them with " | " s . For each of the sequence rules it calls itself recursively to generate a regex for the sub - rule .
def convert(rn) -> str:
        parts = []
        for r in RULES[rn]:
            if isinstance(r, str):
                return r
            else:
                parts.append("".join(convert(x) for x in r))
        return "(" + "|".join(parts) + ")"
def convert ( rn ) -> str : parts = [ ] for r in RULES [ rn ] : if isinstance ( r , str ) : return r else : parts . append ( "" . join ( convert ( x ) for x in r ) ) return "(" + "|" . join ( parts ) + ")"
This function converts a rule number to a regex.
This function converts a rule number to a regex .
"""
        This function converts a rule number to a regex. It uses the ``for`` loop to
        deal with the OR cases, and then joins them with "|"s. For each of the sequence
        rules, it calls itself recursively to generate a regex for the sub-rule.
        """
rn