How can I bind multiple functions to one key?

I read another post and I tried doing:

function a()
	 --script
end

function b()
	--script
end

function ab()
	a()
	b()
end

game:GetService("ContextActionService"):BindAction("ab", ab, false, Enum.KeyCode.E)

It didn't work for me. The post was two years old so it might be outdated, that or I'm doing something wrong. Any help is appreciated.