Pre-defining a function before writing it

Getting Started Newbie Questions
#1

Is it possible to pre-define a function earlier and then fully define it later?  I need to call a function that I can’t define until later because of the procedural way Corona handles code.

Is it possible to define a placeholder for the function?

Something like... local function blah ...code... local function blah() some code end

Is so, what’s the correct syntax?  I’m getting an error trying to access and upscale value or some such.

#2

[lua]

local blah

[/lua]

then

[lua]

blah = function ()

end

[/lua]

#3

[lua]

local blah

[/lua]

then

[lua]

blah = function ()

end

[/lua]