type handler = {getpass : (unit -> Client.passwd_result) option,
adduser : {user : string, passwd : string option} -> string option,
type handler = {getpass : (unit -> Client.passwd_result) option,
adduser : {user : string, passwd : string option} -> string option,
createdb : {user : string, dbname : string} -> string option}
val dbmses : handler StringMap.map ref = ref StringMap.empty
createdb : {user : string, dbname : string} -> string option}
val dbmses : handler StringMap.map ref = ref StringMap.empty