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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 instantiate(self):
 """ Instantiate this object with the supplied parameters in `self.kwds`, or if already instantiated, return the cached instance. """

        if self.instance is None:
            self.instance = checked_call(self.cls, self.kwds)
        #endif
        try:
            self.instance.yaml_src = self.yaml_src
        except AttributeError:
            pass
        return self.instance