func_code: def search(s, letter, pos):
      if pos == len(s):
          print('False')
      elif s[pos] == letter:
          print('True')
      else:
          return search(s, letter, pos + 1)
annotation: def search(s, letter):
      if len(s) == 0:
          return False
      elif s[0] == letter:
          return True
      else:
          return search(s[1:], letter)
  