Need an example on how to use extract_flows_from_cbc_file

[hjia1005]

import flopy
from pypestutils.pestutilslib import PestUtilsLib

# this works
cbb = flopy.utils.binaryfile.CellBudgetFile('model.cbb')
data = cbb.get_data(kstpkper = (0,0))

# now try pestutilslib
lib = PestUtilsLib()

# this doesn't run properly
# it's a usg model so isim = 22 and iprec = 1.
# nzone, geo_zone and ntime don't have issues
result = lib.extract_flows_from_cbc_file(cbcfile = 'model.cbb',
                                         flowtype = 'drn', 
                                         isim = 22,
                                         iprec = 1,
                                         izone = geo_zone.zone.values,
                                         nzone = 68, 
                                         ntime = 70)`

error message: