Literally any code that's like
def function(input1, input2): [code that only manipulates input1 and input2] return output
is functional programming, without having to introduce weird-ass syntax. We already teach people to reduce problems to small, self-contained functions and reduce dependencies as much as possible.
I thought one didn't actually have functional programming until they started having functions that take one or more functions as arguments and return another function (just like one doesn't actually have object-oriented programming until one starts having virtual methods).