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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 setiddname(cls, iddname, testing=False):
 """ Set the path to the EnergyPlus IDD for the version of EnergyPlus which is to be used by eppy. Parameters iddname : str Path to the IDD file. testing : bool Flag to use if running tests since we may want to ignore the `IDDAlreadySetError`. Raises ------ IDDAlreadySetError """

        if cls.iddname == None:
            cls.iddname = iddname
            cls.idd_info = None
            cls.block = None
        elif cls.iddname == iddname:
            pass
        else:
            if testing == False:
                errortxt = "IDD file is set to: %s" % (cls.iddname,)
                raise IDDAlreadySetError(errortxt)