tables with multiple indeces?

["Pavol Severa" <pavol.severa@...>]

there is probably nothing as funny as suggestions from a newbie - so
here is one:

if I got it right, an expression like t[1,2,3] is a syntax error.

would you find it reasonable if instead, whenever it meets a
comma-separated list as an index, lua would try to call the __index
(or __newindex) method of the metatable?