also update in included example

Author: sentrivana

platform-includes/performance/traces-sampler-as-sampler/python.mdx

@@ -6,7 +6,7 @@ def traces_sampler(sampling_context: SamplingContext) -> float:
     # Use the parent sampling decision if we have an incoming trace.
     # Note: we strongly recommend respecting the parent sampling decision,
     # as this ensures your traces will be complete!
-    parent_sampling_decision = sampling_context.get("parent_sampled")
+    parent_sampling_decision = sampling_context["parent_sampled"]
     if parent_sampling_decision is not None:
         return float(parent_sampling_decision)