Canvas Games: Part I - HTML5 Canvas - page 658

context . lineTo ( 10 , 0 );
context . moveTo ( 10 , 1 );
context . lineTo ( − 10 , 10 );
context . lineTo ( 1 , 1 );
context . moveTo ( 1 , − 1 );
context . lineTo ( − 10 , − 10 );