I am trying to build a biword index from a document (i.e.) read a document and split it into two word indexes in a list as below:

doc:

> 
> There have been biographies of Dewey
> that briefly describe his system, but this is the first
> attempt to provide a detailed history of the work that
> more than any other has spurred the growth of
> librarianship in this country and abroad.
> 
> 
> 

```
words=['There have','have been','been biographies','biographies of',etc]

```

Using python code, please help me on how I can do this!