Fix grammar in asyncio-dev.rst (GH-15672)

Automerge-Triggered-By: @ned-deily

diff --git a/Doc/library/asyncio-dev.rst b/Doc/library/asyncio-dev.rst
index b728803619297968d9c57fb4f2b8a5e34566de2e..101e7817a95e98e638dc2d89c5cd34b0b71bb30f 100644 (file)
--- a/Doc/library/asyncio-dev.rst
+++ b/Doc/library/asyncio-dev.rst
@@ -119,7 +119,7 @@ all concurrent asyncio Tasks and IO operations would be delayed
 by 1 second.
 
 An executor can be used to run a task in a different thread or even in
-a different process to avoid blocking block the OS thread with the
+a different process to avoid blocking the OS thread with the
 event loop.  See the :meth:`loop.run_in_executor` method for more
 details.