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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/12/Screen.jack
+
+/**
+ * A library of functions for displaying graphics on the screen.
+ * The Hack physical screen consists of 256 rows (indexed 0..255, top to bottom)
+ * of 512 pixels each (indexed 0..511, left to right). The top left pixel on 
+ * the screen is indexed (0,0).
+ */
+class Screen {
+
+    /** Initializes the Screen. */
+    function void init() {
+    }
+
+    /** Erases the entire screen. */
+    function void clearScreen() {
+    }
+
+    /** Sets the current color, to be used for all subsequent drawXXX commands.
+     *  Black is represented by true, white by false. */
+    function void setColor(boolean b) {
+    }
+
+    /** Draws the (x,y) pixel, using the current color. */
+    function void drawPixel(int x, int y) {
+    }
+
+    /** Draws a line from pixel (x1,y1) to pixel (x2,y2), using the current color. */
+    function void drawLine(int x1, int y1, int x2, int y2) {
+    }
+
+    /** Draws a filled rectangle whose top left corner is (x1, y1)
+     * and bottom right corner is (x2,y2), using the current color. */
+    function void drawRectangle(int x1, int y1, int x2, int y2) {
+    }
+
+    /** Draws a filled circle of radius r<=181 around (x,y), using the current color. */
+    function void drawCircle(int x, int y, int r) {
+    }
+}