(partial comp decor-bevior))
def my_decorator(f): ...
def my_function(...): ...
my_function = my_decorator(my_function)
Function composition is only one of many things you can do with decorators. You could implement a K-combinator with them if you wanted to:
"decorates a function to evaluate that function, but then return x"
def g(*args, **kwargs):
y = x + 1
foo(5) # => 4, but prints 6