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Add positions apart from middle C calculator
- gonna use to help draw notes on a staff - we'll know the height of individual notes, and we know where middle C will be drawn - thus, knowing how far away from middle c, we'll know where to draw each note (y position)
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‎mobile/src/main/java/com/ataulm/notes/PositionsApartFromMiddleCCalculator.java

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package com.ataulm.notes;
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import java.util.HashMap;
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import java.util.Map;
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class PositionsApartFromMiddleCCalculator {
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private static final Map<Key, String[]> CHROMATIC_SCALES_FROM_C = new HashMap<>();
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private static final Note MIDDLE_C = Note.create(60);
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static {
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CHROMATIC_SCALES_FROM_C.put(Key.C_MAJ, new String[]{"C", "C♯", "D", "D♯", "E", "F", "F♯", "G", "G♯", "A", "A♯", "B"});
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CHROMATIC_SCALES_FROM_C.put(Key.G_MAJ, new String[]{"C", "C♯", "D", "D♯", "E", "F♮", "F", "G", "G♯", "A", "A♯", "B"});
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CHROMATIC_SCALES_FROM_C.put(Key.F_MAJ, new String[]{"C", "C♯", "D", "D♯", "E", "F", "F♯", "G", "G♯", "A", "B", "B♮"});
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}
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int positionsApartFromMiddleC(Key key, Note note) {
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if (MIDDLE_C.equals(note)) {
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return 0;
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}
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String[] notes = CHROMATIC_SCALES_FROM_C.get(key);
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if (note.isHigherThan(MIDDLE_C)) {
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return -positionsApart(MIDDLE_C.midi(), note.midi(), notes);
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} else {
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return positionsApart(note.midi(), MIDDLE_C.midi(), notes);
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}
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}
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private int positionsApart(int lowerPitch, int higherPitch, String[] notes) {
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int positionsAway = 0;
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String last = notes[lowerPitch % notes.length];
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for (int pitch = lowerPitch; pitch <= higherPitch; pitch++) {
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String next = notes[pitch % notes.length];
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if (!next.startsWith(last.substring(0, 1))) {
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positionsAway++;
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}
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last = next;
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}
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return positionsAway;
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}
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}

‎mobile/src/test/java/com/ataulm/notes/Fixtures.java

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package com.ataulm.notes;
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class Fixtures {
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static final Note C3 = Note.create(48);
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static final Note C_S3 = Note.create(49);
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static final Note D3 = Note.create(50);
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static final Note D_S3 = Note.create(51);
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static final Note E3 = Note.create(52);
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static final Note F3 = Note.create(53);
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static final Note F_S3 = Note.create(54);
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static final Note G3 = Note.create(55);
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static final Note G_S3 = Note.create(56);
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static final Note A3 = Note.create(57);
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static final Note A_S3 = Note.create(58);
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static final Note B3 = Note.create(59);
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static final Note C4 = Note.create(60);
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static final Note C_S4 = Note.create(61);
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static final Note D4 = Note.create(62);
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static final Note D_S4 = Note.create(63);
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static final Note E4 = Note.create(64);
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static final Note F4 = Note.create(65);
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static final Note F_S4 = Note.create(66);
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static final Note G4 = Note.create(67);
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static final Note G_S4 = Note.create(68);
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static final Note A4 = Note.create(69);
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static final Note A_S4 = Note.create(70);
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static final Note B4 = Note.create(71);
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static final Note C5 = Note.create(72);
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static final Note C_S5 = Note.create(73);
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static final Note D5 = Note.create(74);
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static final Note D_S5 = Note.create(75);
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static final Note E5 = Note.create(76);
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static final Note F5 = Note.create(77);
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static final Note F_S5 = Note.create(78);
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static final Note G5 = Note.create(79);
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static final Note G_S5 = Note.create(80);
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static final Note A5 = Note.create(81);
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static final Note A_S5 = Note.create(82);
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static final Note B5 = Note.create(83);
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}

‎mobile/src/test/java/com/ataulm/notes/PositionsApartFromMiddleCCalculatorTest.java

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package com.ataulm.notes;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.junit.runners.Parameterized;
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import java.util.Arrays;
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import static com.ataulm.notes.Fixtures.A3;
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import static com.ataulm.notes.Fixtures.A4;
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import static com.ataulm.notes.Fixtures.A_S3;
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import static com.ataulm.notes.Fixtures.A_S4;
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import static com.ataulm.notes.Fixtures.B3;
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import static com.ataulm.notes.Fixtures.B4;
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import static com.ataulm.notes.Fixtures.B5;
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import static com.ataulm.notes.Fixtures.C3;
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import static com.ataulm.notes.Fixtures.C4;
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import static com.ataulm.notes.Fixtures.C5;
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import static com.ataulm.notes.Fixtures.C_S4;
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import static com.ataulm.notes.Fixtures.D4;
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import static com.ataulm.notes.Fixtures.D_S4;
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import static com.ataulm.notes.Fixtures.E4;
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import static com.ataulm.notes.Fixtures.F4;
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import static com.ataulm.notes.Fixtures.F_S4;
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import static com.ataulm.notes.Fixtures.G4;
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import static com.ataulm.notes.Fixtures.G_S4;
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import static org.fest.assertions.api.Assertions.assertThat;
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@RunWith(Parameterized.class)
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public class PositionsApartFromMiddleCCalculatorTest {
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@Parameterized.Parameters(name = "Given {1} in Key {0}, expected expectedPositionFromMiddleC: {2}")
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public static Iterable<Object[]> data() {
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return Arrays.asList(new Object[][]{
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{Key.C_MAJ, C3, 7},
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{Key.C_MAJ, A3, 2},
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{Key.C_MAJ, A_S3, 2},
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{Key.C_MAJ, B3, 1},
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{Key.C_MAJ, C4, 0},
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{Key.C_MAJ, C_S4, 0},
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{Key.C_MAJ, D4, -1},
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{Key.C_MAJ, D_S4, -1},
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{Key.C_MAJ, E4, -2},
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{Key.C_MAJ, F4, -3},
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{Key.C_MAJ, F_S4, -3},
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{Key.C_MAJ, G4, -4},
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{Key.C_MAJ, G_S4, -4},
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{Key.C_MAJ, A4, -5},
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{Key.C_MAJ, A_S4, -5},
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{Key.C_MAJ, B4, -6},
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{Key.C_MAJ, C5, -7},
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{Key.C_MAJ, B5, -13},
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{Key.G_MAJ, C3, 7},
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{Key.G_MAJ, A3, 2},
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{Key.G_MAJ, A_S3, 2},
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{Key.G_MAJ, B3, 1},
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{Key.G_MAJ, C4, 0},
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{Key.G_MAJ, C_S4, 0},
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{Key.G_MAJ, D4, -1},
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{Key.G_MAJ, D_S4, -1},
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{Key.G_MAJ, E4, -2},
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{Key.G_MAJ, F4, -3},
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{Key.G_MAJ, F_S4, -3},
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{Key.G_MAJ, G4, -4},
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{Key.G_MAJ, G_S4, -4},
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{Key.G_MAJ, A4, -5},
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{Key.G_MAJ, A_S4, -5},
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{Key.G_MAJ, B4, -6},
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{Key.G_MAJ, C5, -7},
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{Key.G_MAJ, B5, -13},
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{Key.F_MAJ, C3, 7},
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{Key.F_MAJ, A3, 2},
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{Key.F_MAJ, A_S3, 1},
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{Key.F_MAJ, B3, 1},
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{Key.F_MAJ, C4, 0},
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{Key.F_MAJ, C_S4, 0},
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{Key.F_MAJ, D4, -1},
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{Key.F_MAJ, D_S4, -1},
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{Key.F_MAJ, E4, -2},
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{Key.F_MAJ, F4, -3},
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{Key.F_MAJ, F_S4, -3},
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{Key.F_MAJ, G4, -4},
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{Key.F_MAJ, G_S4, -4},
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{Key.F_MAJ, A4, -5},
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{Key.F_MAJ, A_S4, -6},
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{Key.F_MAJ, B4, -6},
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{Key.F_MAJ, C5, -7},
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{Key.F_MAJ, B5, -13}
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});
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}
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@Parameterized.Parameter(0)
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public Key key;
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@Parameterized.Parameter(1)
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public Note note;
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@Parameterized.Parameter(2)
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public int expectedPositionFromMiddleC;
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PositionsApartFromMiddleCCalculator calculator = new PositionsApartFromMiddleCCalculator();
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@Test
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public void positionFromMiddleC() {
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int positionFromMiddleC = calculator.positionsApartFromMiddleC(key, note);
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assertThat(positionFromMiddleC).isEqualTo(expectedPositionFromMiddleC);
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}
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}

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