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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 ecoclass_to_coderef(self, cls):
 """ Map an ECO class to a GAF code This is the reciprocal to :ref:`coderef_to_ecoclass` Arguments --------- cls : str GAF evidence code, e.g. ISS, IDA reference: str ECO class CURIE/ID Return ------ (str, str) code, reference tuple """

        code = ''
        ref = None
        for (code,ref,this_cls) in self.mappings():
            if cls == this_cls:
                return code, ref
        return None, None