 # of the split. In the case of a merge that is three pages. During a balance
 # operation are locking exclusively, at most, three pages at a time.
 #
-# If out balance operation casades so that it requires a balance at every level,
-# we'll descend the tree once for every level. However, the path we follow is
-# almost certain to be in memory, since we're revisting the same path.
+# If out balance operation cascades so that it requires a balance at every
+# level, we'll descend the tree once for every level. However, the path we
+# follow is almost certain to be in memory, since we're revisiting the same
+# path.
 #
 # Also, a balance operation will involve an increasing number of levels with
 # decreasing frequency. A split will most often require that only the leaf page
 # is split. The penultimate pages will be involved in a balance operation at
-# least an order of mangitude less frequently. The pages above the penultimate
+# least an order of magnitude less frequently. The pages above the penultimate
 # branch pages will be involved in a balance operation yet another order of
-# mangniutde less frequently.
+# magnitude less frequently.
 #
 # Conserving descents during balance operations is a false economy. It
 # complicates lock acquisition. It reduces the liveliness of the b&#x2011;tree.
 #
-# The multiple descents will allow searches of the b&#x2011;tree to make progress
-# between balance operations.
+# The multiple descents will allow searches of the b&#x2011;tree to make
+# progress between balance operations.
 #
 # ##### Descent as Unit of Work
 #

    # record could belong.
    unambiguous or= not page.right

    # TK Sibling leaf page? How can there be any other sort of leaf page? Leaf
    # pages done't have children.

    # If we have an ambiguous insert location, peek at the next leaf page to see
    # if the record doesn't really belong to a subsequent leaf page.
    if not unambiguous
      # The lock must held because the balancer can swoop in and prune the
      # ghost first records and thereby change the key. It could not delete
      # the page nor merge the page, but it can prune dead first records.

      #
      @_next or= @_io.lock @_page.right, @_exclusive, true, _

# This is only a problem when we insert a record whose key is not the key used
# to create the mutator. An insert location is always unambiguous if the key is
# the search key used to locate the first page. The key is determined to belong
# inside the leaf page by virtue of a descent of the b&#x2011;tree. That is
# unambiguous.
#
# To know if a subsequent record insert really does belong after the last record
