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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 has_pfn(self, url, site=None):
 """ Wrapper of the pegasus hasPFN function, that allows it to be called outside of specific pegasus functions. """

        curr_pfn = dax.PFN(url, site)
        return self.hasPFN(curr_pfn)