Unpack

unpack (list [, i [, j]])

Returns the elements from the given table. This function is equivalent to

    return list[i], list[i+1], ···, list[j]

except that the above code can be written only for a fixed number of elements. By default, i is 1 and j is the length of the list, as defined by the length operator (see §2.5.5).

Select

Lua Manual - The length operator #

Lua Manual - Variadic Expressions (...)