1. The method of providing language usage guidance with respect to a passage of a document being edited by a user, comprising: generating a hash of the passage being edited; comparing the hash against entries in a database to determine likelihood that the passage is written as intended by the user; and providing alternative language suggestions to the user based in part upon entries in the database; and allowing the user to modify the document by accepting a selected one of the suggestions; a program when run on a local computer to compute a triplet of hashes, wherein each hash consists of a hash for each word in the document, a hash for the word and its preceding word, and a hash for the word and its following word.