367         A dictionary of revlog type to tuples of `(repo, computers, removers)`:

   367         See `revlogutil.sidedata.get_sidedata_helpers`.

   368             * `repo` is used as an argument for computers

   369             * `computers` is a list of `(category, (keys, computer, flags)` that

   370                compute the missing sidedata categories that were asked:

   371                * `category` is the sidedata category

   372                * `keys` are the sidedata keys to be affected

   373                * `flags` is a bitmask (an integer) of flags to remove when

   374                   removing the category.

   375                * `computer` is the function `(repo, store, rev, sidedata)` that

   376                  returns a tuple of

   377                  `(new sidedata dict, (flags to add, flags to remove))`.

   378                  For example, it will return `({}, (0, 1 << 15))` to return no

   379                  sidedata, with no flags to add and one flag to remove.

   380             * `removers` will remove the keys corresponding to the categories

   381               that are present, but not needed.

   382         If both `computers` and `removers` are empty, sidedata are simply not

   383         transformed.

   384         Revlog types are `changelog`, `manifest` or `filelog`.