Do some parser tree caching. This might be important for recursions.

jedi/evaluate/parser_cache.py

@@ -0,0 +1,6 @@
+from jedi.evaluate.cache import evaluator_function_cache
+
+
+@evaluator_function_cache()
+def get_yield_exprs(evaluator, funcdef):
+    return list(funcdef.iter_yield_exprs())