<snapdata remixID="8928325"><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="192" y="154" 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="32" y="10"><block s="clear"></block></script><script x="44" y="58"><block s="doDeclareVariables"><list><l>y value</l></list></block><block s="doSetVar"><l>y value</l><l>0</l></block><block s="doFor"><l>row</l><l>1</l><l>8</l><script><block s="gotoXY"><l>0</l><block var="y value"/></block><block s="doIfElse"><block s="reportEquals"><block s="reportModulus"><block var="row"/><l>2</l></block><l>1</l></block><script><custom-block s="rowA"></custom-block></script><script><custom-block s="rowB"></custom-block></script></block><block s="doChangeVar"><l>y value</l><l>22</l></block></script></block></script><script x="245" y="27"><block s="gotoXY"><l>0</l><l>-20</l></block><custom-block s="rowA"></custom-block><block s="gotoXY"><l>0</l><l>4</l></block><custom-block s="rowB"></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;            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