assertEquals("Test if indices are equal", 0, set.indexOf(a));
assertEquals("Test if indices are equal", 4, set.indexOf(c));
SymbolSet set2 = new SymbolSet();
set2.addSymbol(a);
set2.addSymbol(a);
set2.addSymbol(A);
set2.addSymbol(b);
assertNotEquals("Test if sets are not equal", set, set2);