code: public static Pattern bindsTo()
  	{
  		Pattern p = new Pattern(ProteinReference.class, "first PR");
  		p.add(erToPE(), "first PR", "first simple PE");
  		p.add(linkToComplex(), "first simple PE", "Complex");
  		p.add(new Type(Complex.class), "Complex");
  		p.add(linkToSpecific(), "Complex", "second simple PE");
  		p.add(peToER(), "second simple PE", "second PR");
  		p.add(equal(false), "first PR", "second PR");
  		return p;
  	}
docs: Finds two Protein that appear together in a Complex.
  @return the pattern