title: python function called but not returning value. Should be simple
body: <p>I've got a function:</p>
  
  <pre><code>def user_login(m):
      m = "user_login function called"
      return m
  </code></pre>
  
  <p>Calling it with:</p>
  
  <pre><code>user_login(message)
  </code></pre>
  
  <p>It should change a string, m, and return the result. I know that the function gets called because it throws up an error [user_login() takes exactly 1 argument (0 given)] if I don't put an argument in it. But it doesn't return a string. How can I find out what's wrong?</p>