title: Save user input (string) in Watson assistant
body: <p>I'm building a chat-bot application based on IBM Watson. I need to save the user input into a variable.</p>
  
  <p>I searched the web and I only found tutorials where the input must be of entity sys-(number, day, time, location, person).</p>
  
  <p>In my dialog I ask the user about his identifier. This identifier should be an alphanumerical string.</p>
  
  <p>How can I do so?</p>