useNetCDF3 does not work

[doutriaux1]

cdms2.useNetcdf3()
# or
# value = 0
# cdms2.setNetcdfShuffleFlag(value) ## where value is either 0 or 1
# cdms2.setNetcdfDeflateFlag(value) ## where value is either 0 or 1
# cdms2.setNetcdfDeflateLevelFlag(value) ## where value is a integer between 0 and 9 included
f = cdms2.open("example.nc","w")
f.write(data,id="data")
f.close()

Default warning should mention this instead of the whole long message