+val validDbname = CharVector.all (fn ch => Char.isAlphaNum ch orelse ch = #"_")
+
+type handler = {getpass : (unit -> Client.passwd_result) option,
+ adduser : {user : string, passwd : string option} -> string option,
+ passwd : {user : string, passwd : string} -> string option,
+ createdb : {user : string, dbname : string} -> string option,
+ dropdb : {user : string, dbname : string} -> string option,
+ grant : {user : string, dbname : string} -> string option}