       # Cache the current page length.
       @_io.balancer.unbalanced(@_page)
 
-      # Since we need to fsync anyway, we open the file and and close the file
-      # when we append a JSON object to it. Because no file handles are kept
-      # open, the b&#x2011;tree object can left to garbage collection.
+      # Since we need to fsync anyway, we open the file and close the file when
+      # we append a JSON object to it. Because no file handles are kept open,
+      # the b&#x2011;tree object can left to garbage collection.
       filename = @_io.filename @_page.address
       fd = fs.open filename, "a", 0o644, _
       position = @_io.writeInsert fd, @_page, index, record, _

  #
  # In the leaf page file, a record is stored as JSON string. Not all of the
  # records are loaded when the page loads. Records that are not loaded when the
  # page is loaded, are loaded as needed. The leaf page keeps a map (a
  # JavaScript `Object`) that maps file positions to deserialized records.
  #
  # Because the records are sorted, and because a lookup takes constant time, we
  # can search for a record in a leaf page using binary search in logorithmic
  # time.
  #
  # #### No Duplicates

  # #### Root Branch Page
  #
  # The root page is the first page we consult to find the desired leaf page.
  # Our b&#x2011;tree always contains a root page. The b&#x2011;tree is never so
  # empty that the root page disappears. The root page always has the same
  # address.
  #
  # **TK**: move. Until the root branch page is split, it is both the root
  # branch page and a penultimate branch page.
  #
  # ### Keys and First Records
  #
  # We said that it is only possible for an insertion to insert a into the left
  # most child leaf page of a penultimate branch page a record less than the
  # least record. We can say about a tree rooted by an interior branch page,
  # that an insertion is only able to insert into the left most leaf page in the
  # *entire tree* a record less than the least record.
  #
  # **TK**: Confusing.
  #
  # Using our example tree with one root interior page, with two penultimate
  # branch page children, we cannot insert a record into the right penultimate
  # branch page that will displace the first record of its left most child
  # branch, because that first record is the key for the right penultimate
  # branch page. When we insert a record that is less than the key, the search
  # for a leaf page to store the record goes to the left of the key. It cannot
  # descend into the right penultimate branch page, so it is impossible for it
  # be inserted into left child of the right penultimate branch page, so the
