<snapdata remixID="8923698"><project name="U2L4-checkerboard_SV" app="Snap! 5.1, http://snap.berkeley.edu" version="1"><notes></notes><thumbnail>data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAKAAAAB4CAYAAAB1ovlvAAAG9UlEQVR4Xu3dW2iXdRzH8e/m/js4dR42d3In9a/oiMyOlJYaWJlm4EUXXRRoSBdeBYoK0VVERKhFIGkYhXYwMoSi0DltztKpaFPUHcSp6UqQUlNBWTwbNp0Gv8/4Pvz5j7e3fj7fZ//v8/KZ2549/4yurq4u4w8bSNEGMgCYos1z2O4NABAIKd0AAFO6fg4OQAykdAMATOn6OTgAMZDSDQAwpevn4GkDMC87Qz5b9fPn2KMtR6TexUS2lR1qkTpR+OrkKrmzZGS5rWtolHqTRo20A8VDpU4Uzjt6Su7sfXaW3dfRpvWqx5ptqQvuALDPqgDYuxAA3oaDK2DPMrgCBl9cfYMABKCvKHEaAAEokvGNAxCAvqLEaQAEoEjGNw5AAPqKEqcBEIAiGd84AAHoK0qcBkAAimR84wAEoK8ocRoAASiS8Y13zHhIHrg+I2G7zpyTesMTWbZ69HCpE4VfOXtB7qwcX2UTrl6RehcyMu2NM39InSj8aXmh3Fl9I8MOdP4p9UpKS23Trj3BnbS5GcGmVAe/qFvBZSU1tqauXuqVDcm3tkr9ZPXnbpPdc2fb1Pbj0sd3NifPxh88JnWicH/u1lmYX2Qb9zVJx0pOmGiHm8M/PgD2WS8AexcCwNtxcAXs3gZXQOmC7BgGIAAdOemjAAhAXY1jA4AAdOSkjwIgAHU1jg0AAtCRkz4KgADU1Tg2AAhAR076KAACUFfj2AAgAB05yaMu3a//LPid0hpbv6tBOlZx/mBrKBshdaJwsuWs3Nkye6bVnjwh9c7n5tn031qlThRuSZbLnaVDR9u3Bw5KvXHJpO0+dDS4kzY/C+Z2rJ5zyi+mB9v2DQIQgL6ixGkABKBIxjcOQAD6ihKnARCAIhnfOAAB6CtKnAZAAIpkfOMABKCvKHEaAAEokvGNAxCAvqLEaQAEoEjGNw5AAPqKEqcBEIAiGec4t2N1L5TfC3Z2FTwOgAAMxhJHEIAAjMNV8EwAAjAYSxxBAAIwDlfBMwEIwGAscQQBCMA4XAXPBCAAg7HEEQQgAONwFTwTgAAMxhJHEIAAjMNV8EwAAjAYSxxBAAIwDlehM6eNrQiN/pd7c9J4q738l9S7lJFpizo6pU4U/rKiSO58YAlrOP271CsfnGvvjxoqdaLwS6e19/uIOm9PrLFx/1zWjjW6xMq//j64w6M5+qzqYiLbyg61BC/wVrA/78OxZGS5rWtolI7FozmkdfmFuR+wZ5cA9DMlTQIgACUw3mEAAtDblDQPgACUwHiHAQhAb1PSPAACUALjHQYgAL1NSfMACEAJjHcYgAD0NiXNAyAAJTDeYQAC0NuUNG9yQZ6Uj8IfPv2UJVuPSb3LiWxb0Hpa6kThH6uK5c5HRWPsu6b9Uq96eIGtLciVOlH4mVP6DRYfT3/MKjtOSsfKqqqx0q07gjtpczOCcTtW90nl0RzBtp2DAASgMyltHAABqIlxTgMQgM6ktHEABKAmxjkNQAA6k9LGARCAmhjnNAAB6ExKGwdAAGpinNMABKAzKW0cAAGoiXFOAxCAzqS0cQAEoCbGN83tWD375BfTfV0FTwMgAIOxxBEEIADjcBU8E4AADMYSRxCAAIzDVfBMAAIwGEscQQACMA5XwTMBCMBgLHEEAQjAOFwFzwQgAIOxxBEEIADjcBU8E4AADMYSRxCAAIzDVfDMmzMfDM7eCi7vyrHNrW1Srygnxxor9ff8SLackY4ThTdOmWwPX/lb6p3JyLSZJzqkThRuSY6RO69fN9vWob2uyjEVVv9LU/CxeDRHn1WVDcm3tsrC4AXeCuYdPSV3ds+dbVPbj0s9Hs0hrcsxzP2A3csEoKMpaRQAASiB8Q4DMOUAs3NybdFri624uMTqtv9kO+vvfgxbcsJEO9wc/kg8/g/I/wH/91KxML/INu7r/YJiy9Yf7MV5z3XnMwcNsorKKps7d75VV1fZhk/W2ZEjzQbA29a5rKTG1tTVS9divgjpXVdfgNHfrF23wRYvevWunWZlJezJGbPsiWnTbcWKlcE75wrIFTD4CjhsWIEVji629tYTd3SyEjm2dNlyu3nzhrW1tdpnn28CYLQBroC9DvrzdrJ9r4CPT5thjQ31lpObZ3Oen2e1tbX2655G2/XzTrt+7Vr3wfgUzKfge159PAC++94q29+01+p3bLfOzns/cxqAAIwNYMjnVQACEIAh/1LkDN8HTPn3AUPO2cC9Ar78QsjrvyOzasgo23y4WeoV5uXaltIRUicKT2s/J3fWPvKA1V44L/U6sxK2oB83IzSMLZWOE4XfGpRv21papd6Yikr74qtvgjvp822Y4JdEMJ02AMB0OlsD8GMF4AA8qen0kgCYTmdrAH6sAByAJzWdXtK/vBnRICxCtT8AAAAASUVORK5CYII=</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><watcher scope="Sprite" s="xPosition" style="normal" x="10.104166666666629" y="10.104166666666643" color="74,108,212" hidden="true"/><sprite name="Sprite" idx="1" x="207.00000000000043" y="-144" heading="90" scale="1" volume="100" pan="0" rotation="1" draggable="true" costume="0" color="8,5,0,1" pen="tip" id="9"><costumes><list struct="atomic" id="10"></list></costumes><sounds><list struct="atomic" id="11"></list></sounds><blocks></blocks><variables></variables><scripts><script x="30" y="63"><block s="receiveGo"></block><custom-block s="draw Checkerboard with %n rows"><l>8</l></custom-block></script><script x="303" y="69.00000100000005"><block s="receiveKey"><l><option>space</option></l></block><block s="clear"></block></script></scripts></sprite><watcher scope="Sprite" s="yPosition" style="normal" x="3.1041666666666288" y="62.32291868749998" color="74,108,212" hidden="true"/></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="draw Checkerboard with %&apos;row#&apos; rows" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input></inputs><script><block s="gotoXY"><l>-113</l><l>-104</l></block><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><block s="gotoXY"><l>-113</l><l>-104</l></block><block s="changeYPosition"><l>40</l></block><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><block s="gotoXY"><l>-113</l><l>-24</l></block><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><block s="gotoXY"><l>-113</l><l>16</l></block><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><block s="gotoXY"><l>-113</l><l>56</l></block><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><block s="gotoXY"><l>-113</l><l>96</l></block><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><block s="gotoXY"><l>-113</l><l>136</l></block><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><block s="gotoXY"><l>-113</l><l>-144</l></block><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><block-definition s="%&apos;first number&apos; divisible by %&apos;divisible by&apos; ?" type="reporter" category="operators"><header></header><code></code><translations></translations><inputs><input type="%s"></input><input type="%s"></input></inputs><script><block s="doIf"><block s="reportEquals"><block s="reportModulus"><block var="first number"/><block var="divisible by"/></block><l>0</l></block><script><block s="doReport"><block s="reportBoolean"><l><bool>true</bool></l></block></block></script></block><block s="doReport"><block s="reportBoolean"><l><bool>false</bool></l></block></block></script></block-definition><block-definition s="Even? %&apos;Even number??&apos;" type="reporter" category="operators"><header></header><code></code><translations></translations><inputs><input type="%s"></input></inputs><script><block s="doIf"><custom-block s="%s divisible by %s ?"><block var="Even number??"/><l>2</l></custom-block><script><block s="doReport"><block s="reportBoolean"><l><bool>true</bool></l></block></block></script></block><block s="doReport"><block s="reportBoolean"><l><bool>false</bool></l></block></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>