Get fetches the document specified by the `key` argument.
Everything other than `.Path` is ignored.
Note that once a document is read, it WILL be cached for the
duration of this object, unless you call `Reset`
Get fetches the document specified by the `key` argument, making
a HTTP request if necessary.
Note that once a document is read, it WILL be cached for the
duration of this object, unless you call `Reset`