Fiz deste jeito esta correto? "Costumizei" um pouco kkk...
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var tela = document.querySelector("canvas");
var pincel = tela.getContext("2d");
pincel.fillStyle = "darkgreen";
pincel.fillRect(0, 0, 600, 400);
pincel.fillStyle = "green";
pincel.fillRect(200, 0, 200, 400);
pincel.fillStyle = "black";
pincel.fillRect(120, 70, 120, 120);
pincel.fillStyle = "black";
pincel.fillRect(360, 70, 120, 120);
pincel.fillStyle = "black";
pincel.fillRect(240, 190, 120, 150);
pincel.fillStyle = "black";
pincel.fillRect(170, 260, 70, 400);
pincel.fillStyle = "black";
pincel.fillRect(360, 260, 70, 400);
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