Question: How can make substitutions of general expressions?

I need to sustitute many similar expressions. 
Somthing like:

subs( {f(x1)=h(x1), f(x2)=h(x2)...., f(xn)=h(xn)}, expression)

How can I ask Maple to substitute 

f(anything) = h(same thing)? 

(In Mathematica this can be done with x_) 

Even more general, how can I substitute, for example, 

F(f(x)) = H(h(x))
where f(x) is really 'anything'? 

Thanks! Max

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