Pull fix for example custom tracker field from pyrocore

pyroscope/pyrocore#105

Author: kannibalox

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+- Use all trackers when aggregating in example custom field code
+  (credit goes to @kchiem: https://github.com/pyroscope/pyrocore/pull/105)
+
 ## [2.2.1] - 2022-10-24
 
 ### Fixed

docs/examples/custom-fields-trackers.py

@@ -8,7 +8,7 @@ def _custom_fields():
     # Add rTorrent attributes not available by default
     def get_tracker_field(obj, name, aggregator=sum):
         "Get an aggregated tracker field."
-        return aggregator(obj.rpc_call("t.multicall", ["", f"t.{name}="])[0])
+        return aggregator([t[0] for t in obj.rpc_call("t.multicall", ["", f"t.{name}="])])
 
     yield engine.DynamicField(
         int,