python/bash (newbie) Split very long character sting into smaller character blocks with character overlap
===

Sorry for the very basic question, but I'm not even sure how to Google the question. 

In essence, I have a long string of characters that I need to split into smaller chunks, but the chunks need to overlap. 

The length of the output string and overlap to be either hard-coded (not preferred) or as an input variable. 

**I'd be more than willing to do this myself if someone can direct me to a good tutorial on python, where something similar to this is addressed.**

**Thanks for reading!**

Example:

Starting with this in a text file: 

    -----------------------------------------------------

Getting this: 

    ---------------------
        ---------------------
            ---------------------
               etc...

With the output being written like this:

    >
    ---------------------
    >
    ---------------------
    >
    ---------------------
