Check if a value's a function.
npm install @is-(unknown)/is-function@is-(unknown)/is-functioncheck if something's a function
``js
const assert = require("assert-fn")
const isFunction = require("@is-(unknown)/is-function")
assert(isFunction(function(){}))
assert(isFunction(()=>{}))
assert(isFunction(function*(){}))
assert(isFunction(async function(){}))
assert(!isFunction("not a function"))
``