ref
Atomically increments the reference count of @user_content_filter by one.
This function is MT-safe and may be called from any thread.
Return
the @user_content_filter passed in.
Since
2.24
Atomically increments the reference count of @user_content_filter by one.
This function is MT-safe and may be called from any thread.
the @user_content_filter passed in.
2.24