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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 onCall(self, n):
 #pylint: disable=invalid-name """ Adds a condition for when the stub is called. When the condition is met, a special return value can be returned. Adds the specified call number into the condition list. For example, when the stub function is called the second time, it will return "#": stub.onCall(1).returns("#") Without returns/throws at the end of the chain of functions, nothing will happen. For example, in this case, although 2 is in the condition list, nothing will happen: stub.onCall(2) Args: n: integer, the call # for which we want a special return value. The first call has an index of 0. Return: a SinonStub object (able to be chained) """

        cond_oncall = n + 1
        return _SinonStubCondition(copy=self._copy, oncall=cond_oncall, cond_args=self._cond_args, cond_kwargs=self._cond_kwargs)