<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def search(self, string, default=None):
 """Use re.search to find the result :rtype: list"""

        default = default if default else []
        result = [item[1] for item in self.container if item[0].search(string)]
        if self.ensure_mapping:
            assert len(result) < 2, "%s matches more than one pattern: %s" % (
                string,
                result,
            )
        return result if result else default