         # exclusive and shared locks to clear.
         key = tierOrAddress.cache[address] = @key address, 0, _
       key
-
-  # Write the branches to a file as a JSON string. We tuck the tier properties
-  # into an object before we serialize it, so that it is easy deserialize.
-  writeBranches: (tier, suffix, _) ->
-    filename = @filename tier.address, suffix
-    record = [ tier.penultimate, tier.next?.address, tier.addresses ]
-    json = JSON.stringify(record) + "\n"
-    fs.writeFile filename, json, "utf8", _
-
-  # Read branches from a brach tier file and assign the tier properties to the
-  # given tier object.
-  #
-  # TODO: Move link to head always, to maintain MRU.
-  readBranches: (tier, _) ->
-    filename = @filename tier.address
-    json = fs.readFile filename, "utf8", _
-    [ penultimate, next, addresses ] = JSON.parse json
-    extend tier, { penultimate, next, addresses }
 
   # TODO Consider: can't I always just rewrite and link?
   rewriteBranches: (tier, _) ->

    @head.previous  = @head
    @nextAddress    = 0

  # Create the database detroying any exisiting database.

  # &mdash;


  # TODO Very soon.
  close: (_) ->
#
#
# A branch page file contains a single object that includes the array of page
# addresses that reference the branch page's children.
#
# The branch page file also stores a penultimate flag, and the address of the
# next sibling of the branch
# page.
# The keys associated with the child addresses are not stored in the
# branch page.
#
# Put another way, each branch element in a branch page represents a leaf page.
# The leaf pages are sorted by the tree collation. The object value used to sort
# the branch page is first element in the sorted leaf page.
#
# TODO Okay, what? I'm forgetting that I need the addresses to inner tiers as
# well as to leaf tiers, both, when the tier is not penultimate. Descending is
# not going to work, that is going to load the entire tree into memory quickly.
#
# Hmm... Maybe not. Tree four deep means loading only a particular path. It
# ensures that we read lock our way down the tree to get our record. Although, I
# believe I thought long and hard about this, and jumping down to the leaves
# wasn't a problem.
#
# We only need to store the sorted array of the leaf tier addresses in our
# branch tier, since we can obtain the object used to collate the address

  # Link tier to the head of the MRU list.
  link: (entry) ->
