Ahh! self == the instance

class 'A'

local this
function A:Initialize()
    this = self
    self.value = 0
end

function A:DoMath()
    self.value = self.value + 1
end

function A:PrintValue()
    Print(self.value)
end

local a = A()
a:Initialize()

a:PrintValue() //output = 0
a.value = 20
a:PrintValue() //output = 20

A.DoMath(a) //increment to 21
a:DoMath()  //increment to 22

Print(ToString(a == this)) //output = true

Print(a.value) //output = 22
a:PrintValue() //output = 22