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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 lookup_hlr(self, phonenumber, params=None):
 """Retrieve the information of a specific HLR lookup."""

        if params is None: params = {}
        return HLR().load(self.request('lookup/' + str(phonenumber) + '/hlr', 'GET', params))