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var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = "darkgreen";
pincel.fillRect(0,0,350, 300);
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pincel.fillRect(50,60,90,90);
pincel.fillRect(210,60,90,90);
pincel.fillRect(140,150,70,100);
pincel.fillRect(100,190,40,110);
pincel.fillRect(210,190,40,110);
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