meteor invoking a callback after callback

This question relates to calling 2 callback functions

Let me know if you want me to paste my entire code but first I'll explain without.

I have set up 3 functions where 2 of them are 'callable'

functionOne
functionTwo
functionThree

I have set up my callback correctly and able to invoke functionTwo after functionOne like this...

functionOne(functionTwo) // this is fine

How do invoke functionThree after functionTwo? The callback has been defined in the parameters of functionTwo.

I tried functionOne(functionTwo(functionThree)) but this is wrong

Help please?