Signal understanding

An utterance which signals understanding. Any utterance that does not explicitly signal non-understanding implicitly indicates understanding

-Example (1):

  Explainer:	['The main thing about black hole to remember is', "that it's just, like I said, how the earth holds you down,", 'the black hole pulls you in, as well.', 'Now, try and take the ball from me, black hole--']
   Explainee:	['Why do you hold it so tight?']
   Explainer:	["I'm holding it tight to show you", "then when you're trying to pull it,", 'a black hole will really hold onto it with its gravity.']
   Explainee:	['I got it.'] ---> Signal understanding