[Tutor] AttributeError: 'module' object has no attribute 'start'

[jason sam]

Hi All,
I am new to wxPython.I have made a simple GUI that contains a button and by
pressing that button i am calling another .py file(top_block.py)...But i am
getting error using the command:

top_block.start()

The error is:

AttributeError: 'module' object has no attribute 'start'

The code is as attached.I am using python 2.7.3.Any improvements in the
code are also welcome.The same error is received when i
use'top_block.run()'.Is there any alternative to this commands?

Regards,
Ali
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