title: RecursionError when using gtts on Python
body: <p>I am using the gtts(google text to speech) package to turn several Chinese Text to Speech. However, I got a lot of RecursionError: maximum recursion depth exceeded. </p>
  
  <p>The code is easy:</p>
  
  <pre><code>from gtts import gTTS
  
  tts = gTTS(text=sentence, lang='zh')
  tts.save(r"E:\Project\audioData\zh%d.wav"%(1))
  </code></pre>
  
  <p>The full error messeage is showed as photo
  <a href="https://i.stack.imgur.com/PXHzH.png" rel="nofollow noreferrer">Error Messeage</a></p>
  
  <pre><code>Traceback (most recent call last):
  File "E:\Independent Study\Project\test.py", line 3, in &lt;module&gt;
  tts = gTTS(text=sentence, lang='zh')
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 97, in __init__
  text_parts = self._tokenize(text, self.MAX_CHARS)
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 169, in _tokenize
  min_parts += self._minimize(p, " ", max_size)
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 178, in _minimize
  return [thestring[:idx]] + self._minimize(thestring[idx:], delim, max_size)
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 178, in _minimize
  return [thestring[:idx]] + self._minimize(thestring[idx:], delim, max_size)
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 178, in _minimize
  return [thestring[:idx]] + self._minimize(thestring[idx:], delim, max_size)
  [Previous line repeated 983 more times]
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 176, in _minimize
  if self._len(thestring) &gt; max_size:
  File "C:\Users\Yuchen Liu\AppData\Local\Programs\Python\Python36\lib\site-
  packages\gtts\tts.py", line 154, in _len
  return len(unicode(text))
  RecursionError: maximum recursion depth exceeded
  </code></pre>
  
  <p>Please Help!</p>