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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 if_match(self):
 """Optimistic concurrency control."""

        match = True
        if_match = self.request.META.get('HTTP_IF_MATCH')
        if if_match:
            etag = self.etag()
            if etag != if_match:
                match = False
        return match