Then don't do that.

Edit your code block over at the left margin as you would normally edit any code. Then do a block insert of 4 spaces down the left side of your code block. That's how I do it.

    line of code
    line of code
        indented line of code
    line of code

In vim, after editing your code like you usually would:

    Go to the front of the top line,
    Ctrl-V to enter visual block mode (Ctrl-Q on windows),
    jjj to the bottom line,
    I (capital I) to insert at the front,
    space space space space,
    escape.

I did exactly that to create the above two blocks.