src/getFunction.js
function getFunction(value, replacement) {
    return baseGetType(_.isFunction, _.noop, value, replacement);
}
function getFunction(value, replacement) {
    return baseGetType(_.isFunction, _.noop, value, replacement);
}
function getFunction ( value , replacement ) { return baseGetType ( _ . isFunction , _ . noop , value , replacement ) ; }
Returns value if a function, otherwise a default function.

@static
@memberOf _
@category Lang
@param {mixed} value Source value
@param {number} replacement Custom default if value is invalid type.
@return {number} Final function.
@example

_.getFunction(null);
// => function () {}
Returns value if a function otherwise a default function .