Sets the drag information that is associated with this tree
        widget item for the given format.
        
        :param      format | <str>
                    value  | <variant>

def setDragData(self, format, value):
        """
        Sets the drag information that is associated with this tree
        widget item for the given format.
        
        :param      format | <str>
                    value  | <variant>
        """
        if value is None:
            self._dragData.pop(nativestring(format), None)
        else:
            self._dragData[nativestring(format)] = value