title: Python temporarily change letter to lower case
body: <p>I have a list that looks like this:</p>
  
  <p><code>separate=[['I','wnet','to','the','mal,'],['and','bouht','a','new','shirt.'],['What','did','you','do','todya?']]</code></p>
  
  <p>I'm going to run this through a program which will identify the misspelled words and replace them with the correct word but the list of words in the <code>Webster Dictionary</code> that I am using only uses lowercase letters. Can I temporarily change all of the letters to lowercase but then in the end return the original upper and lower case words?</p>
  
  <p>I know about <code>str.upper()</code> and <code>str.lower()</code> and <code>set.capitalize</code>.</p>
  
  <p>It seems like I want to use something like <code>str.capwords()</code> but inversely... I want to split the list into words(already done) and then make capital letters lower case. </p>