code: def get_sentence(start=None, depth=7):
      ''' follow the grammatical patterns to generate a random sentence '''
      if not GRAMMAR:
          return 'Please set a GRAMMAR file'
  
      start = start if start else GRAMMAR.start()
  
      if isinstance(start, Nonterminal):
          productions = GRAMMAR.productions(start)
          if not depth:
              # time to break the cycle
              terminals = [p for p in productions if not isinstance(start, Nonterminal)]
              if len(terminals):
                  production = terminals
          production = random.choice(productions)
  
          sentence = []
          for piece in production.rhs():
              sentence += get_sentence(start=piece, depth=depth-1)
          return sentence
      else:
          return [startf get_sentence(start=None, depth=7):
      ''' follow the grammatical patterns to generate a random sentence '''
      if not GRAMMAR:
          return 'Please set a GRAMMAR file'
  
      start = start if start else GRAMMAR.start()
  
      if isinstance(start, Nonterminal):
          productions = GRAMMAR.productions(start)
          if not depth:
              # time to break the cycle
              terminals = [p for p in productions if not isinstance(start, Nonterminal)]
              if len(terminals):
                  production = terminals
          production = random.choice(productions)
  
          sentence = []
          for piece in production.rhs():
              sentence += get_sentence(start=piece, depth=depth-1)
          return sentence
      else:
          return [start]
docs: follow the grammatical patterns to generate a random sentence