Returns the 0-1 percentage opacity value for this node.
        
        :return     <float>

def opacity( self ):
        """
        Returns the 0-1 percentage opacity value for this node.
        
        :return     <float>
        """
        if self.isIsolateHidden():
            return 0.1
        
        opacity = super(XNode, self).opacity()
        layer = self.layer()
        if layer:
            return layer.opacity() * opacity
        
        return opacity