from cdo import *

cdo = Cdo()
#cdo.debug = True

print(cdo.diffn(input='-topo -topo'))
print(cdo.diff(input='-topo -topo'))

print(cdo.diffn(input='-topo -mulc,3 -topo'))
print(cdo.diff(input='-topo -mulc,3 -topo'))