code: private Iterator<Tuple> getBindingsFor( VarTupleSet tuples, VarDef var)
      {
      return
        IteratorUtils.chainedIterator(
          tuples.getUnused( var),
          IteratorUtils.chainedIterator(
            tuples.getUsed( var),
            tuples.getUsedOnce( var)));
      }
docs: Returns a set of 1-tuples containing the bindings for the given variable that are applicable to the given test case.