# pytest-dev__pytest-6116
# Loki Mode Multi-Agent Patch
# Attempts: 1

I can see the existing patch format. Let me verify the correct line numbers by checking the actual pytest source file structure. Based on the architect's analysis and the existing patch, I need to generate a proper patch that adds `--co` as a shortcut for `--collect-only`.

--- a/src/_pytest/main.py
+++ b/src/_pytest/main.py
@@ -109,6 +109,7 @@ def pytest_addoption(parser: Parser) -> None:
         dest="collectonly",
         help="only collect tests, don't execute them.",
     )
     group.addoption(
+        "--co",
         "--collect-only",
         "--collectonly",
         action="store_true",