solving the problem of strict aliases. Now a strict alias
#! x = y will be transformed into #! x = _dummyForStrictAlias y while checking. The new predefined symbol _dummyForStrictAlias has the type of the identity function. This application will be removed in the backend conversion phase. In this case x and y will simply get the same sequence number (see module backendpreprocess). Then the binding can be ignored.