<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def evaluate(self, instance, step, extra):
 """Evaluate the current ContainerAttribute. Args: obj (LazyStub):
 a lazy stub of the object being constructed, if needed. containers (list of LazyStub):
 a list of lazy stubs of factories being evaluated in a chain, each item being a future field of next one. """

        # Strip the current instance from the chain
        chain = step.chain[1:]
        if self.strict and not chain:
            raise TypeError(
                "A ContainerAttribute in 'strict' mode can only be used "
                "within a SubFactory.")

        return self.function(instance, chain)