title: Changing capitalization with for loops and list comprehension
body: <p>I have a assignment where I need to</p>
  <blockquote>
  <p>sometimes it might be useful to convert text from lowerCamelCase to snake_case. The main trick is to find the correct place where to insert an underscore. Let's make a rule that it's right before a capital letter of the next word. If the first letter is capitalized, convert it to lowercase and don't forget to insert an underscore before it.</p>
  </blockquote>
  <p>I wrote my code and for some reason it doesn't return anything, it's completely empty, my ide says I have no errors</p>
  <pre><code>word = input()
  new_word = ''
  for char in word:
      if char.isupper():
          new_word.join('_' + char.lower())
      else:
          new_word.join(char)
  print(new_word)
  </code></pre>
  <p>The assignment runs multiple tests with different words, and here they are</p>
  <blockquote>
  <p>Sample Input 1:</p>
  </blockquote>
  <blockquote>
  <p>python</p>
  </blockquote>
  <blockquote>
  <p>Sample Output 1:</p>
  </blockquote>
  <blockquote>
  <p>python</p>
  </blockquote>
  <blockquote>
  <p>Sample Input 2:</p>
  </blockquote>
  <blockquote>
  <p>parselTongue</p>
  </blockquote>
  <blockquote>
  <p>Sample Output 2:</p>
  </blockquote>
  <blockquote>
  <p>parsel_tongue</p>
  </blockquote>
  <p>I legitimately don't see any reason why it's not printing, any ideas why</p>