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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_window_size(self, windowHandle='current'):
 """ Gets the width and height of the current window. :Usage: :: driver.get_window_size() """

        command = Command.GET_WINDOW_SIZE
        if self.w3c:
            if windowHandle != 'current':
                warnings.warn("Only 'current' window is supported for W3C compatibile browsers.")
            size = self.get_window_rect()
        else:
            size = self.execute(command, {'windowHandle': windowHandle})

        if size.get('value', None) is not None:
            size = size['value']

        return {k: size[k] for k in ('width', 'height')}