local generic_func = function(table, x)
    return table.pos + x
end

local obj = { pos = 1}
local unrelated = { pos = "42" }

function obj:func1(x)
    return self.pos + x
end

function obj.func2(object, x)
    return object.pos+x
end

obj.func3 = generic_func

-- identical results, no matter how you call it
print(obj:func1(2))
print(obj.func1(obj, 2))
print(obj:func2(2))
print(obj.func2(obj, 2))
print(obj:func3(2))
print(obj.func3(obj, 2))
print(generic_func(obj, 2))

-- function from "obj" runs on unrelated table
print(obj.func1(unrelated, 2))