Attempts to return x as data.
datafy will return the value of clojure.protocols/datafy. If
the value has been transformed and the result supports
metadata, :clojure.datafy/obj will be set on the metadata to the
original value of x.

Returns (possibly transformed) v in the context of coll and k (a
key/index or nil). Callers should attempt to provide the key/index
context k for Indexed/Associative/ILookup colls if possible, but not
to fabricate one e.g. for sequences (pass nil). nav will return the
value of clojure.core.protocols/nav.