Pythonesk "from ... import" in Lua, copying parts of a library into the global table

from.lua

-- CC0, see http://creativecommons.org/publicdomain/zero/1.0/ etcetera, etcetera

function from(source, which)
	local t = require(source)
	local function import (which)
		if which == '*' then
			for k, v in pairs(t) do
				if _G[k] == nil then
					_G[k] = v
				end
			end
		else
			for i, v in ipairs(which) do
				_G[v] = t[v]
			end
		end
	end
	if which then
		return import(which)
	else
		return import
	end
end

--[[ usage:

from 'lib' '*'
from 'lib2' {'ball', 'rectangle', 'close'}
from ('lib3', '*')
]]