That actually may be incorrect, it should be this:

local first = (select(
  1, -- uses +1 rule
  result()
))

Note the parenthesis around the call to select, this is necessary because select returns all arguments at the specific index, rather than just one.

Something like this:

local first, second = select(1, result()), 'second'

is incorrect because if result() returns more than one value, the second value will be assigned to second and the 'second' will be dropped.

This has correct behavior:

local first, second = (select(1, result())), 'second'