Update the display label to reflect the value of the parameter.

def updateDisplayLabel(self, value=None):
        """Update the display label to reflect the value of the parameter."""
        if value is None:
            value = self.param.value()
        opts = self.param.opts
        if isinstance(self.widget, QtWidgets.QAbstractSpinBox):
            text = asUnicode(self.widget.lineEdit().text())
        elif isinstance(self.widget, QtWidgets.QComboBox):
            text = self.widget.currentText()
        else:
            text = asUnicode(value)
        self.displayLabel.setText(text)