CSOM - update resource availability

does anyone know how to update resource availability in CSOM? i need to rewrite some code written in PSI and can't find a way to do it. Any ideas?

here is my code in PSI

 updateDs.Tables["ResourceAvailabilities"].Rows[0]["RES_AVAIL_UNITS"] = 80;

            SvcResource.ResourceDataSet.ResourceAvailabilitiesRow resAvailRow = updateDs.ResourceAvailabilities.NewResourceAvailabilitiesRow();

            resAvailRow.RES_UID = resourceRow.RES_UID;
            resAvailRow.SetRES_AVAIL_FROMNull();
            resAvailRow.SetRES_AVAIL_TONull();
            resAvailRow.RES_AVAIL_UNITS = 80;
            updateDs.ResourceAvailabilities.AddResourceAvailabilitiesRow(resAvailRow);

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tatiana