This function returns the keys.
keys(x, keytype, ...)
x
MSEADb object such as MSEA.Ath.pb.db
MSEADb
MSEA.Ath.pb.db
keytype
MSEADb What kind of key user want to specify
...
MSEADb Other parameter
The keys for using select functions
Kozo Nishida
showMethods("keys")