In subscribe, run a callback instead of printing the message.

[rdt12]

Description

As a developer, I would like to use the scaffolding provided by the subscribe module and run my own code instead of printing the message.

There are a number of ways to accomplish this. Here are two examples::

1. factor the code out of _main into a new function, say guts, and have _main and a new function named, say subscribe call guts with a callback function. _main could use print_message as the callback

2. Add a callback argument to _main that defaults to print_message.

Definition of Done

A test program is written that defines a callback and ensures that the callback is called.

[myNameIsPatrick]

@rdt12, just wanted to check in to see if you think there's still value in doing something like this after #82, which drastically simplified the subscribe main code (https://github.com/scimma/hop-client/blob/master/hop/subscribe.py#L49-L59).

[rdt12]

@myNameIsPatrick I guess I haven't looked at the code since July. It looks like most of the details are now buried in the io.Stream class so I agree that there is no point to this and it can be closed.

[rdt12]

Based on my last comment, closing this issue.