title: Call method in a class which called the current class
body: <p>How could I call the method 'z'? Which is he best way for this?
  And to an object?</p>
  
  <p>File test1.py:</p>
  
  <pre><code>from test2 import Test2
  
  class Test1(object):
      def __init__(self):
          pass
      def a(self):
          print("Running a of Test1")
          test_instance2 = Test2()
      def z(self):
          print("Running z of Test1")
  
  if __name__ == '__main__':
      test_instance = Test1()
      test_instance.a()
  </code></pre>
  
  <p>File test2.py:</p>
  
  <pre><code>class Test2:
      def __init__(self):
          self.b()
      def b(self):
          print('Running b of Test2')
          print('Here I want to call method z of Test1') # &lt; How call z in Test1?
  </code></pre>
  
  <p>Run as:</p>
  
  <pre><code>python test1.py
  </code></pre>
  
  <p>Thanks in advance! :) I'm so sorry the elementary question :$</p>