Function dependence flexibility

edit

I'd like to declare an unknown function f. If I had one variable x, I would write

f=function('f')(x)

Instead, I would like to declare this function with a variable list (or tuple) that has unknown length at the beginning of the program. For example,

f=function('f')(x,y)

has two variables or

f=function('f')(x,y,t)

has three.

I can get a list (or tuple) containing my variables just before the function declaration:

vars=[x,y,z,t]

Then how can I declare my function like

f=function('f')(vars)

?