title: Python while not True or False
body: <p>Is it possible to use a while loop to keep asking for an input value if the value supplied is not 'yes' or 'no'?  e.g </p>
  
  <pre><code>someVar = None
  
  while someVar is not (True or False):
  
    someVar = str.lower(input())
  
    if someVar == 'yes':
        someVar = True
  
    elif someVar== 'no':
        someVar = False
  </code></pre>