### Question:
Symbol extends ERE { @Override public String toString() { return refToString.get(this); } private  Symbol(); static Symbol get(String name); @Override EREType getEREType(); @Override boolean equals(Object o); @Override int compareTo(Object o); @Override ERE copy(); @Override String toString(); @Override boolean containsEpsilon(); @Override ERE derive(Symbol s);  }### Answer:
@Test public void testString() { assertEquals("one", one.toString()); assertEquals("two", two.toString()); }