Run the given source code in the interpreter.
This is essentially the same as calling the builtin "exec"
with this interpreter, using the __dict__ of its __main__
module as both globals and locals.
There is no return value.
If the code raises an unhandled exception then an ExecutionFailed
exception is raised, which summarizes the unhandled exception.
The actual exception is discarded because objects cannot be
shared between interpreters.
This blocks the current Python thread until done. During
that time, the previous interpreter is allowed to run
in other threads.