static IActivityMonitorLineSender FilterLogLine( this IActivityMonitor @this, LogLevel level, string fileName, int lineNumber ) { Debug.Assert( (level & LogLevel.IsFiltered) == 0 ); if( @this.ShouldLogLine( level, fileName, lineNumber ) ) { return new ActivityMonitorLineSender( @this, level | LogLevel.IsFiltered, fileName, lineNumber ); } return ActivityMonitorLineSender.FakeLineSender; }