<snapdata remixID="8927298"><project name="U2L4-checkerboard_SV" app="Snap! 5.1, http://snap.berkeley.edu" version="1"><notes></notes><thumbnail>data:image/png;base64,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</thumbnail><stage name="Stage" width="480" height="360" costume="0" color="255,255,255,1" tempo="60" threadsafe="false" volume="100" pan="0" lines="flat" ternary="true" codify="false" inheritance="false" sublistIDs="false" scheduled="false" id="1"><pentrails>data:image/png;base64,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</pentrails><costumes><list struct="atomic" id="2"></list></costumes><sounds><list struct="atomic" id="3"></list></sounds><variables></variables><blocks></blocks><scripts></scripts><sprites><sprite name="Sprite" idx="1" x="-178.38630806845967" y="177.99511002444987" heading="90" scale="1" volume="100" pan="0" rotation="1" draggable="true" costume="0" color="8,5,0,1" pen="tip" id="8"><costumes><list struct="atomic" id="9"></list></costumes><sounds><list struct="atomic" id="10"></list></sounds><blocks></blocks><variables></variables><scripts><script x="39" y="69.99999999999994"><custom-block s="draw black square size %n"><l>40</l></custom-block></script><script x="32" y="118.99999999999994"><custom-block s="draw red square size %n"><l>40</l></custom-block></script><script x="301" y="208"><block s="clear"></block><custom-block s="Checker Board size: %s"><l>8</l></custom-block></script></scripts></sprite></sprites></stage><hidden></hidden><headers></headers><code></code><blocks><block-definition s="set flag %&apos;which&apos; to %&apos;tf&apos;" type="command" category="sensing"><header></header><code></code><translations></translations><inputs><input type="%s" readonly="true"><options>Presentation mode&#xD;Retina display support&#xD;Long form input dialog&#xD;Plain prototype labels&#xD;Input sliders&#xD;Execute on slider change&#xD;Clicking sound&#xD;Turbo mode&#xD;Flat design&#xD;Keyboard editing&#xD;Table support&#xD;Table lines&#xD;Visible stepping&#xD;Thread safe scripts&#xD;Prefer smooth animations&#xD;Flat line ends&#xD;Codification support&#xD;Inheritance support</options></input><input type="%b"></input></inputs><script><block s="doRun"><block s="reportJSFunction"><list><l>which</l><l>tf</l></list><l>var   stage = this.parentThatIsA(StageMorph),&#xD;        ide = stage.parentThatIsA(IDE_Morph),&#xD;        world = stage.parentThatIsA(WorldMorph);&#xD;&#xD;if (tf != !!tf) return;&#xD;&#xD;try{&#xD;ide.savingPreferences = false;&#xD;&#xD;switch (which) {&#xD;    case &apos;Presentation mode&apos;:&#xD;        if (tf != ide.isAppMode) ide.toggleAppMode();&#xD;        break;&#xD;    case &apos;Retina display support&apos;:&#xD;        if (tf != isRetinaEnabled()) ide.toggleRetina();&#xD;        break;&#xD;    case &apos;Long form input dialog&apos;:&#xD;        if (tf != InputSlotDialogMorph.prototype.isLaunchingExpanded)&#xD;            ide.toggleLongFormInputDialog();&#xD;        break;&#xD;    case &apos;Plain prototype labels&apos;:&#xD;        if (tf != BlockLabelPlaceHolderMorph.prototype.plainLabel)&#xD;            ide.togglePlainPrototypeLabels();&#xD;        break;&#xD;    case &apos;Input sliders&apos;:&#xD;        MorphicPreferences.useSliderForInput = tf;&#xD;        break;&#xD;    case &apos;Execute on slider change&apos;:&#xD;        ArgMorph.prototype.executeOnSliderEdit = tf;&#xD;        break;&#xD;    case &apos;Clicking sound&apos;:&#xD;        if (tf != !!BlockMorph.prototype.snapSound)&#xD;            BlockMorph.prototype.toggleSnapSound();&#xD;        break;&#xD;    case &apos;Turbo mode&apos;:&#xD;        if (tf != stage.isFastTracked)&#xD;            ide.toggleFastTracking();&#xD;        break;&#xD;    case &apos;Flat design&apos;:&#xD;        if (tf == MorphicPreferences.isFlat) break;&#xD;        if (tf)&#xD;            ide.flatDesign();&#xD;        else&#xD;            ide.defaultDesign();&#xD;        break;&#xD;    case &apos;Keyboard editing&apos;:&#xD;            ScriptsMorph.prototype.enableKeyboard = tf;&#xD;        break;&#xD;    case &apos;Table support&apos;:&#xD;            List.prototype.enableTables = tf;&#xD;        break;&#xD;    case &apos;Table lines&apos;:&#xD;                TableMorph.prototype.highContrast = tf;&#xD;        break;&#xD;    case &apos;Visible stepping&apos;:&#xD;        if (tf != Process.prototype.enableSingleStepping)&#xD;            ide.toggleSingleStepping();&#xD;        break;&#xD;    case &apos;Thread safe scripts&apos;:&#xD;        stage.isThreadSafe = tf;&#xD;        break;&#xD;    case &apos;Prefer smooth animations&apos;:&#xD;        if (tf != (StageMorph.prototype.frameRate &gt; 0))&#xD;            ide.toggleVariableFrameRate();&#xD;        break;&#xD;    case &apos;Flat line ends&apos;:&#xD;        SpriteMorph.prototype.useFlatLineEnds = tf;&#xD;        break;&#xD;    case &apos;Codification support&apos;:&#xD;        if (tf != StageMorph.prototype.enableCodeMapping) {&#xD;            StageMorph.prototype.enableCodeMapping = tf;&#xD;            ide.currentSprite.blocksCache.variables = null;&#xD;            ide.currentSprite.paletteCache.variables = null;&#xD;            ide.refreshPalette();&#xD;        }&#xD;        break;&#xD;    case &apos;Inheritance support&apos;:&#xD;        if (tf != StageMorph.prototype.enableInheritance) {&#xD;            StageMorph.prototype.enableInheritance = tf;&#xD;            ide.currentSprite.blocksCache.variables = null;&#xD;            ide.currentSprite.paletteCache.variables = null;&#xD;            ide.refreshPalette();&#xD;        }&#xD;        break;&#xD;};&#xD;}&#xD;finally {&#xD;ide.savingPreferences = false;&#xD;};&#xD;</l></block><list><block var="which"/><block var="tf"/></list></block></script></block-definition><block-definition s="draw brick, length: %&apos;length&apos; width: %&apos;width&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input><input type="%n"></input></inputs><script><block s="setColor"><color>145,26,68,1</color></block><custom-block s="set flat line ends to %b"><block s="reportBoolean"><l><bool>true</bool></l></block></custom-block><block s="setSize"><block var="width"/></block><block s="down"></block><block s="forward"><block var="length"/></block><block s="up"></block></script></block-definition><block-definition s="set flat line ends to %&apos;flag&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%b"></input></inputs><script><custom-block s="set flag %s to %b"><l>Flat line ends</l><block var="flag"/></custom-block></script></block-definition><block-definition s="draw black square size %&apos;size&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input></inputs><script><block s="setColor"><color>8,5,0,1</color></block><custom-block s="set flat line ends to %b"><block s="reportBoolean"><l><bool>true</bool></l></block></custom-block><block s="setSize"><block var="size"/></block><block s="down"></block><block s="forward"><block var="size"/></block><block s="up"></block></script></block-definition><block-definition s="draw red square size %&apos;size&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input></inputs><script><block s="setColor"><color>255,47,31,1</color></block><custom-block s="set flat line ends to %b"><block s="reportBoolean"><l><bool>true</bool></l></block></custom-block><block s="setSize"><block var="size"/></block><block s="down"></block><block s="forward"><block var="size"/></block><block s="up"></block></script></block-definition><block-definition s="Checker Board size: %&apos;size&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%s"></input></inputs><script><block s="doDeclareVariables"><list><l>row</l><l>x-value</l><l>y-value</l></list></block><block s="doSetVar"><l>x-value</l><block s="xPosition"></block></block><block s="doSetVar"><l>y-value</l><block s="yPosition"></block></block><block s="doSetVar"><l>row</l><l>1</l></block><block s="doRepeat"><block var="size"/><script><block s="doIfElse"><block s="reportEquals"><block s="reportModulus"><block var="row"/><l>2</l></block><l>0</l></block><script><custom-block s="Row b"></custom-block></script><script><custom-block s="Row a"></custom-block></script></block><block s="doChangeVar"><l>row</l><l>1</l></block><block s="doChangeVar"><l>y-value</l><l>40</l></block><block s="gotoXY"><block var="x-value"/><block var="y-value"/></block></script></block></script></block-definition><block-definition s="Row a" type="command" category="pen"><header></header><code></code><translations></translations><inputs></inputs><script><block s="doRepeat"><l>4</l><script><custom-block s="draw black square size %n"><l>40</l></custom-block><custom-block s="draw red square size %n"><l>40</l></custom-block></script></block></script></block-definition><block-definition s="Row b" type="command" category="pen"><header></header><code></code><translations></translations><inputs></inputs><script><block s="doRepeat"><l>4</l><script><custom-block s="draw red square size %n"><l>40</l></custom-block><custom-block s="draw black square size %n"><l>40</l></custom-block></script></block></script></block-definition></blocks><variables></variables></project><media name="U2L4-checkerboard_SV" app="Snap! 5.1, http://snap.berkeley.edu" version="1"></media></snapdata>