'Well, what IS the song, then?' said Alice,
who was by this time completely bewildered.
'I was coming to that,' the Knight said. 'The
song really IS "A-SITTING ON A GATE": and the
tune's my own invention.'
As Martin Gardner pointed out, this can't be right:
this is just another name. The Knight should have
said "The song really _is_" and then sung it
immediately.