<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def decompress(self, value):
 """ Takes the sequence of ``AssignedKeyword`` instances and splits them into lists of keyword IDs and titles each mapping to one of the form field widgets. """

        if hasattr(value, "select_related"):
            keywords = [a.keyword for a in value.select_related("keyword")]
            if keywords:
                keywords = [(str(k.id), k.title) for k in keywords]
                self._ids, words = list(zip(*keywords))
                return (",".join(self._ids), ", ".join(words))
        return ("", "")