Alternative form for family formats that serialises the typehint
as a field value on the same level as the other parts (assumed to
be a SexpData), i.e. to match our legacy format.
Linear Supertypes
SexpFormat[T], SexpWriter[T], SexpReader[T], AnyRef, Any
Alternative form for family formats that serialises the typehint as a field value on the same level as the other parts (assumed to be a SexpData), i.e. to match our legacy format.