title: How do you check in python whether a string contains only numbers?
body: <p>How do you check whether a string contains only numbers?</p>
  
  <p>I've given it a go here. I'd like to see the simplest way to accomplish this.</p>
  
  <pre><code>import string
  
  def main():
      isbn = input("Enter your 10 digit ISBN number: ")
      if len(isbn) == 10 and string.digits == True:
          print ("Works")
      else:
          print("Error, 10 digit number was not inputted and/or letters were inputted.")
          main()
  
  if __name__ == "__main__":
      main()
      input("Press enter to exit: ")
  </code></pre>