code: function getFunction(value, replacement) {
      return baseGetType(_.isFunction, _.noop, value, replacement);
  }
docs: 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 () {}