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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_tokens(self, locations=None, extent=None):
 """Obtain tokens in this translation unit. This is a generator for Token instances. The caller specifies a range of source code to obtain tokens for. The range can be specified as a 2-tuple of SourceLocation or as a SourceRange. If both are defined, behavior is undefined. """

        if locations is not None:
            extent = SourceRange(start=locations[0], end=locations[1])

        return TokenGroup.get_tokens(self, extent)