private IEnumerable <Variable> AvailableLinearVars(Absy absy)
{
HashSet <Variable> availableVars =
new HashSet <Variable>(linearTypeChecker.AvailableLinearVars(absyMap[absy]));
// A bit hackish, since GlobalVariableLayerRange and LocalVariableIntroLayer return maximum layer range
// respectively minimum layer if called on non-global respectively non-local variable.
availableVars.RemoveWhere(v =>
!civlTypeChecker.GlobalVariableLayerRange(v).Contains(layerNum) ||
layerNum < civlTypeChecker.LocalVariableIntroLayer(v)
);
return(availableVars);
}
