How to get the original expression string from *vm.Program?

[100vlx]

How to get the original expression string from *vm.Program?

The source field in *vm.Program is now lowercase...

[hesining]

I think it is necessary to provide a way to obtain the original expression, because ’Compile‘ and ’Run‘ may not be in the same place.Sometimes I need to know the original expression when executing 'Run'. It would be more convenient if this method is provided.