They do a few preventive measures.

> we first check that it is safe to run by ensuring there are no import statements, special variables that begin with __, or calls to exec and eval. Then, we call Python’s exec function with the code as the input string and two dictionaries that form the scope of that code execution: (i) globals, containing all APIs that the generated code might call, and (ii) locals, an empty dictionary which will be populated with variables and new functions defined during exec. If the LMP is expected to return a value, we obtain it from locals after exec finishes.