input: 
  def remove_whitespace(word_list):
      return [word.replace(" ", "") for word in word_list]
  
  assert remove_whitespace(['Hello  World  ', 'Hi  there', 'Good  Morning']) == ['HelloWorld', 'Hithere', 'GoodMorning']
  
output:     for i in range(len(word_list)):
          word_list[i] = word_list[i].replace(" ", "")
      return word_list