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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_security_group_id(self, name):
 """ Take name string, give back security group ID. To get around VPC's API being stupid. """

        # Memoize entire list of groups
        if not hasattr(self, '_security_groups'):
            self._security_groups = {}
            for group in self.get_all_security_groups():
                self._security_groups[group.name] = group.id
        return self._security_groups[name]