<canvas width="600" height="400"></canvas>
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var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = "green";
pincel.fillRect(0, 0, 350, 300);
pincel.fillStyle = "black";
pincel.fillRect(50, 40, 90, 90);
pincel.fillStyle = "black";
pincel.fillRect(210, 40, 90, 90);
pincel.fillStyle = "black";
pincel.fillRect(130, 125, 90, 110);
pincel.fillStyle = "black";
pincel.fillRect(100, 190, 40, 110);
pincel.fillStyle = "black";
pincel.fillRect(210, 190, 40, 110);
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