make the preview area wider
proofreding
serving /posts/:id/edit
json serving a single post
refactoring step 1 - introduce lookup() function
make lookup() async: take a callback function instead of returning a post object.
pull the model.lookup() call from caller to callee
the new function generate a new post with a .body field
get rid of the body param in the callback
reduce nesting levels by early exits
model.lookup() -> model.fetchBody() - eliminate mixup with the lookup() function in site.js"
DRY: replace forEach() with a lookup() call
reorder: place caller after callee