    def get_padding_lengths(self, indexed_tokens: IndexedTokenList) -> Dict[str, int]:
        """
        This method returns a padding dictionary for the given `indexed_tokens` specifying all
        lengths that need padding.  If all you have is a list of single ID tokens, this is just the
        length of the list, and that's what the default implementation will give you.  If you have
        something more complicated, like a list of character ids for token, you'll need to override
        this.
        """
        padding_lengths = {}
        for key, token_list in indexed_tokens.items():
            padding_lengths[key] = max(len(token_list), self._token_min_padding_length)
        return padding_lengths
This method returns a padding dictionary for the given `indexed_tokens` specifying all
lengths that need padding.  If all you have is a list of single ID tokens, this is just the
length of the list, and that's what the default implementation will give you.  If you have
something more complicated, like a list of character ids for token, you'll need to override
this.
allennlp/data/token_indexers/token_indexer.py