### Question:
Sequence extends ArrayList<Symbol> implements AbstractSequence { public String toDotString() { if(size() == 0) return "\\#epsilon"; StringBuilder sb = new StringBuilder(); for(Symbol s : this) { sb.append(s.toDotString()); sb.append("\\ "); } String ret = sb.toString(); return ret.substring(0,ret.length() - 2); } Sequence(int size);  Sequence();  Sequence(ArrayList<Symbol> symbols); String toString(); String toDotString(); Sequence copy(); static void printSequenceArray(Sequence[] arr); @Override int dotLength(); @Override void getImpl(StringBuilder sb, Map<Symbol, Integer> symToNum);  }### Answer:
@Test public void dotStringTest() { assertEquals("\\#epsilon", empty.toDotString()); assertEquals("a\\ b", sequenceAB.toDotString()); assertEquals("a\\ b\\ c", sequenceABC.toDotString()); }