title: Return True, False and None in Python
body: <p>I have function <code>a</code> call function <code>b</code> (returns <code>True</code> or <code>False</code> to <code>a</code>), afterwards function <code>a</code> can return the result to be printed.</p>
  
  <pre><code>class C:
      ...
  
      def a(self, data):
  
          p = self.head
          return self.b( p,data)
  
      def b(self, p, data):
  
          current = p
          if current.data == data:
              return True
          else:
              return False
  
  
  if __name__=="__main__":  
  
      x = C()
      print(x.a(1))
  </code></pre>
  
  <p>Sometimes it returns None eventhough it is intended to be <code>True</code>. I'm not sure what happened?</p>