Tracking blocks of code that have been previously loaded into the interpreter #21
Description
While reviewing editor plugins that are similar to this one, I noticed that a lot of them leverage Jupyter/IPython's concept of cells in order to mark code that has already been sent to their REPL. As much as I like the notebook interface (and would love to have something similar in this plugin), the addition of cells will unfortunately force us to track edits in the current buffer and would likely interfere with free-form editing of the input buffer.
However, one of the features which seemed useful and still within scope of the plugin is the ability to distinguish lines that haven't been submitted from those that have been. This can probably be done using the sign-support feature of the editor. Ideally, it'd be neat to sign a block that has just recently been submitted and sign previously submitted lines differently. Then, lines that haven't been submitted can just remain unsigned. This would end up making the present interpreter state a lot more apparent without having to review the output window.