private static void RegisterExistingCharacter(Link character)
 {
     if (character.Source == Net.Character && character.Linker == Net.ThatHas)
     {
         var code = character.Target;
         if (code.Source == Net.Code && code.Linker == Net.ThatIsRepresentedBy)
         {
             var charCode = (char)LinkConverter.ToNumber(code.Target);
             _charactersToLinks[charCode]  = character;
             _linksToCharacters[character] = charCode;
         }
     }
 }
 private static void RegisterExistingLetter(Link letter)
 {
     letter.WalkThroughReferersAsSource(referer =>
     {
         if (referer.Linker == Net.Has)
         {
             var target = referer.Target;
             if (target.Source == Net.Code && target.Linker == Net.ThatIsRepresentedBy)
             {
                 var charCode = (char)LinkConverter.ToNumber(target.Target);
                 _charactersToLinks[charCode] = letter;
                 _linksToCharacters[letter]   = charCode;
             }
         }
     });
 }