Given a list of numeric sequences, returns the corresponding strings

def convert_to_strings(self, sequences, sizes=None):
        """Given a list of numeric sequences, returns the corresponding strings"""
        strings = []
        for x in xrange(len(sequences)):
            seq_len = sizes[x] if sizes is not None else len(sequences[x])
            string = self._convert_to_string(sequences[x], seq_len)
            strings.append(string)
        return strings