title: How to call a function from another class in python?
body: <p>I'm very new to python and Sikuli software. :( 
  I was trying to call a function from another class.
  Here is a class which contains the functions.</p>
  
  <pre><code>class Reader():
      def getUsername():
          ....
          return username
  
      def getAddress():
          .....
          return address
  </code></pre>
  
  <p>Here is another class which calls the functions stated above.</p>
  
  <pre><code>class DisplayInfo():
      reader = Reader()
      uName = reader.getUsername()
      addr = reader.getAddress()
      ......
      ......
  </code></pre>
  
  <p>But when I ran DisplayInfo class, I got this error.</p>
  
  <pre><code>uName = reader.getUsername()
  TypeError: getUsername() takes no arguments (1 given)
  </code></pre>
  
  <p>Could anyone help me solve this? Thanks so much in advance!</p>