include Contents.S with type t = contents
type t = contents
The type for user-defined contents.
Merge function. Evaluates to
`Conflict msg if the values cannot be merged properly. The arguments of the merge function can take
None to mean that the key does not exists for either the least-common ancestor or one of the two merging points. The merge function returns
None when the key's value should be deleted.
of_key r k is the contents object in
r with key
None if no such contents object exists.