Update advanced_source/coding_ddpg.py

Co-authored-by: Vincent Moens <[email protected]>

Author: malfet

advanced_source/coding_ddpg.py

@@ -70,7 +70,10 @@
 # TorchRL prefers spawn method, that restricts creation of  ``~torchrl.envs.ParallelEnv`` inside
 # `__main__` method call, but for the easy of reading the code switch to fork
 # which is also a default spawn method in Google's Colaboratory
-multiprocessing.set_start_method("fork")
+try:
+    multiprocessing.set_start_method("fork")
+except RuntimeError:
+    assert multiprocessing.get_start_method() == "fork"
 # sphinx_gallery_end_ignore