AttributeError: 'SymbolicTransformer' object has no attribute '_program'

This error message suggests that you are trying to access an attribute called `_program` of an object of class `SymbolicTransformer`, but this attribute does not exist in the object.

There are a few possible reasons why you might be encountering this error:

1. You may have misspelled the attribute name, or assumed that it exists when it does not. Check the documentation for `SymbolicTransformer` to see if `_program` is a valid attribute.

2. The object you are trying to access might not have been properly initialized or constructed. Make sure that you are creating an instance of `SymbolicTransformer` correctly, and that you are passing in the correct arguments.

3. There could be a bug or issue with the `SymbolicTransformer` class itself. Check for any known issues or updates to the library you are using, and consider reporting the problem to the developer if you cannot find a solution.