When I run example , it shows a error .

[jonkiky]

! /usr/bin/python

-- coding:utf-8 --

import sumpy

doc1 = "This is the text for document1. It is for explanatory purposes..."
doc2 = "This is another document text..."
doc3 = "And yet another document..."
inputs = [doc1, doc2, doc3]
print "lede summarizer:"
print sumpy.lede(inputs)
print "\ntextrank summarizer:"
print sumpy.textrank(inputs)
print "\ncentroid summarizer:"
print sumpy.centroid(inputs)

And Errors shows as below.

Traceback (most recent call last):
File "D:\01 Ualbnay Courses\0550 Information Recieve\Project\summarization library\sumpy-master\Summary.py", line 10, in
print sumpy.lede(inputs)
File "D:\01 Ualbnay Courses\0550 Information Recieve\Project\summarization library\sumpy-master\sumpy\simple.py", line 5, in lede
return s.summarize(inputs)
File "D:\01 Ualbnay Courses\0550 Information Recieve\Project\summarization library\sumpy-master\sumpy\system_base.py", line 31, in summarize
input_df, ndarray_data)
File "D:\01 Ualbnay Courses\0550 Information Recieve\Project\summarization library\sumpy-master\sumpy\system_base.py", line 106, in process_input
self, input_df, ndarray_data)
File "D:\01 Ualbnay Courses\0550 Information Recieve\Project\summarization library\sumpy-master\sumpy\annotators_preprocessor.py", line 60, in process
cols = input_df.columns.difference(processed_df.columns).tolist()
AttributeError: 'Index' object has no attribute 'difference'