Explain `SynapseError` and `FederationError` better (#14191)

Explain `SynapseError` and `FederationError` better

Spawning from https://github.com/matrix-org/synapse/pull/13816#discussion_r993262622

1 files changed, 8 insertions, 0 deletions

diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py

index 28097664b4..59e351595b 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -481,6 +481,14 @@ class FederationServer(FederationBase):
                     pdu_results[pdu.event_id] = await process_pdu(pdu)
 
         async def process_pdu(pdu: EventBase) -> JsonDict:
+            """
+            Processes a pushed PDU sent to us via a `/send` transaction
+
+            Returns:
+                JsonDict representing a "PDU Processing Result" that will be bundled up
+                with the other processed PDU's in the `/send` transaction and sent back
+                to remote homeserver.
+            """
             event_id = pdu.event_id
             with nested_logging_context(event_id):
                 try: