7.3. can-add-child: Can a given parent have a
given child?
This function is a predicate that specifies whether a new
child taxon of a given rank can be added to an existing parent
taxon. See Section 15.6, “Hier.canParentHaveChild()” for
the tests for which taxa can occur as children of a given
taxon.
nomcompile3
# can-add-child ( hier, parent, childRank ) ==
# if (parent.rank < child.rank) and
# (there are no missing required ranks between parent.rank
# and child.rank) and
# ((parent has no children) or
# (childRank == rank of parent's last child)) ->
# True
# else -> False
