less imports

pymistral/cdo_post.py

 import glob
 import os
 import warnings
+import logging
 
 import pandas as pd
 import xarray as xr
 
-import cdo
-import logging
-from .setup import my_system
+try:
+    import cdo
+    from .setup import my_system
+    cdo = cdo.Cdo()
+    cdo.forceOutput = True
 
 warnings.simplefilter('ignore')
 xr.set_options(keep_attrs=True)
 
-cdo = cdo.Cdo()
-cdo.forceOutput = True
 
 
 expid = 'asp_esmControl_PMassim_1850_ATMTSIDICALKNUT_over_2006'