ModuleNotFoundError

[liufy11]

When I use vcf file to run Loter as follow:
loter_cli -r data/ceu.vcf data/yri.vcf -a data/mex.vcf -f vcf -o tmp.vcf.txt -n 8 -v

the screen says :

Loading reference haplotypes

Using 2 reference populations
loading file data/ceu.vcf
Traceback (most recent call last):
File "/home/liufy/miniconda2/bin/loter_cli", line 11, in
load_entry_point('loter==0.1', 'console_scripts', 'loter_cli')()
File "/home/liufy/miniconda2/lib/python2.7/site-packages/loter-0.1-py2.7-linux-x86_64.egg/loter/cli.py", line 129, in main
H_ref.append(load_data(file, args.format, args.verbose))
File "/home/liufy/miniconda2/lib/python2.7/site-packages/loter-0.1-py2.7-linux-x86_64.egg/loter/cli.py", line 59, in load_data
except (ModuleNotFoundError):
NameError: global name 'ModuleNotFoundError' is not defined