-- Create a map of key, value pairs.
local planets = {
    Mercury = 1,
    Venus   = 2,
    Earth   = 3,
    Mars    = 4,
    Jupiter = 5,
    Saturn  = 6,
    Uranus  = 7,
    Neptune = 8,
    Pluto   = 9
}

-- Print it
-- Note that order is not guaranteed.
for k, v in planets do print(k, v) end
print()

-- Create a new one by inverting the key, value pairs.
local planets2 = planets:invert()

-- Print it.
-- Now treated as an array with indices 1 to 9
-- which guarantees order.
for k, v in planets2 do print($"{k} {v}") end