Returns a color for the inputed key (used in pie charts).
        
        :param      key | <str>
        
        :return     <QColor>

def keyColor( self, key ):
        """
        Returns a color for the inputed key (used in pie charts).
        
        :param      key | <str>
        
        :return     <QColor>
        """
        self._keyColors.setdefault(nativestring(key), self.color())
        return self._keyColors[nativestring(key)]