callbacks-mix-input-and-output.js

// when performing an async operation that requires a callback
// we have to immediately provide that callback
// and would need to maintain or pass around a reference to 
// the callback in our codebase if we wanted to handle the
// response in a different place from where we started the async
// process.
httpGet(function callback() {
  // we have to provide this callback immediately
  // when starting this operation and cannot do
  // it at a later point.
})

// best we can do to split the async op from our reaction to
// it is to extract the callback as a standalone function.
// Even so, this is just positional separation, not temporal
// or functional. We still maintain a direct reference to our
// async operation => tight coupling
httpGet(callback)

// ... somewhere else
function callback() {

}