Thank you so very much !!!
QgsProject.instance().writeEntry('Digitizing', '/SnappingMode', 'advanced')
QgsProject.instance().snapSettingsChanged.emit()
This did the trick for me. I'm so surprised the answer wasn't easy to
find...
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Sent from: http://osgeo-org.1560.x6.nabble.com/QGIS-Developer-f4099106.html