Passing data between steps

Applications can write to the flow memory, and any later step can read it with a Handlebars template:

```step
application: calculator
method: multiply
description: Multiply the previous result by 2, using memory
parameters:
  body:
    a: "{{ memory.lastResult }}"
    b: 2
test:
  status: 200
  body:
    result: 84
```

Which keys a method writes (and reads) is part of its documentation, through the @memory JSDoc tag — the application page lists them per method.

Memory lives for one run of one flow: it starts empty every time you press Run.