Parameter implements Expression { public int compareTo(Expression e) { if (this == e) return 0; if (e instanceof Parameter) { Parameter o = (Parameter) e; return order - o.order; } else { return getClass().getName().compareTo(e.getClass().getName()); } } Parameter(); void visit(ExpressionVisitor visitor); Class<?> typeConstraint(); Iterable<Expression> children(); int compareTo(Expression e); boolean equals(Object o); int hashCode();  }
@Test public void isAsymptotic() { Parameter param2 = new Parameter(); assertTrue(param2.compareTo(param) > 0); assertTrue(param.compareTo(param2) < 0); }