add_irregular_rule      Add a custom rule for making "deregularizing" a
                        word
add_plural_rule         Add a custom rule for making a word plural
add_singular_rule       Add a custom rule for making a word singular
add_uncountable_rule    Make a word "uncountable"
is_plural               Test plural state of a word
pluralize               Pluralize a word
singularize             Singularize a word
