code: private Result searchCompatible(PType to, PType from, boolean paramOnly)
  	{
  		TypePair pair = new TypePair(to, from);
  		int i = done.indexOf(pair);
  
  		if (i >= 0)
  		{
  			return done.get(i).result; // May be "Maybe".
  		} else
  		{
  			done.add(pair);
  		}
  
  		// The pair.result is "Maybe" until this call returns.
  		pair.result = test(to, from, paramOnly);
  
  		return pair.result;
  	}
docs: Search the {@link #done} vector for an existing comparison of two types before either returning the previous
  result, or making a new comparison and adding that result to the vector.
  
  @param to
  @param from
  @return Yes or No.