ClearSelectedMapFeatures 接口的使用？

 public void ClearSelectedMapFeatures(ESRI.ArcGIS.Carto.IActiveView activeView, ESRI.ArcGIS.Carto.IFeatureLayer featureLayer)
        {
            if (activeView == null || featureLayer == null)
            {
                return;
            }
            ESRI.ArcGIS.Carto.IFeatureSelection featureSelection = featureLayer as ESRI.ArcGIS.Carto.IFeatureSelection; // Dynamic Cast

            // Invalidate only the selection cache. Flag the original selection
            activeView.PartialRefresh(ESRI.ArcGIS.Carto.esriViewDrawPhase.esriViewGeoSelection, null, null);

            // Clear the selection
            featureSelection.Clear();

            // Flag the new selection
            activeView.PartialRefresh(ESRI.ArcGIS.Carto.esriViewDrawPhase.esriViewGeoSelection, null, null);
        }

看到官方给的清除地图已选元素，但是不知道这个接口要怎么用？
函数的两个实参要怎么写呢？比如我要在一个mousedown函数里调用这个接口，具体实参应该写什么呢？
不是很理解两个参数的含义，有哪位大神可以帮忙解答下？

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        if (activeView == null || featureLayer == null)
        {
            return;
        }
        ESRI.ArcGIS.Carto.IFeatureSelection featureSelection = featureLayer as ESRI.ArcGIS.Carto.IFeatureSelection; // Dynamic Cast

        // Invalidate only the selection cache. Flag the original selection
        activeView.PartialRefresh(ESRI.ArcGIS.Carto.esriViewDrawPhase.esriViewGeoSelection, null, null);

if (activeView == null || featureLayer == null)
{
return;
}
ESRI.ArcGIS.Carto.IFeatureSelection featureSelection = featureLayer as ESRI.ArcGIS.Carto.IFeatureSelection; // Dynamic Cast

    // Invalidate only the selection cache. Flag the original selection
    activeView.PartialRefresh(ESRI.ArcGIS.Carto.esriViewDrawPhase.esriViewGeoSelection, null, null);

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