@staticmethod
    def _clean_input(input):
        """
        Remove stop words from the input
        
        @return: The cleaned string and a set of removed stop words
        @rtype: str, frozenset
        """
        
        # Cheap and nasty tokenisation
        cleaned = []
        removed = set()
        for word in input.split(' '):
            if word in LibrarySearchQuery.STOP_WORDS:
                removed.add(word)
            else:
                cleaned.append(word)
        return ' '.join(cleaned), frozenset(removed)
dataset/ETHPy150Open mollyproject/mollyproject/molly/apps/library/models.py/LibrarySearchQuery._clean_input/original