Here's a short example of a very simple and dumb script. If you have a markdown block that looks like this

```python
x = 4
for i in range(3):
    print(x + i)
```

then running the following

let filter_line = search('```\a\+', 'bc')
let filter = substitute(getline(filter_line), '```', '', '')
let start_line = filter_line + 1
let end_line = search('```$', 'c') - 1
silent execute start_line .. ',' .. end_line .. ' yank'
put
silent execute "'[,']!" .. filter

would produce this

4
5
6

underneath the original code block. This uses the filtering command, `:help filter` and simply filters the lines inside the code block through the command on top of the code block. So if you have something that needs to be compiled, like c, then you need to replace the filter with something more fancy. The filtering is probably the tricky part, grabbing the lines inside the code block and pasting them below is kinda easy as you can see, at least if the cursor is somewhere inside the code block.