Passing References as Values

If Ruby is pass by value and the values it passes are references, then why doesn’t the code below change ans when I call set_it?

#! /usr/bin/env ruby

def set_it(data)
	data = 8888

if __FILE__ == $0

	ans = 1234
	p ans

I think I found the answer or part of the answer.

The reason is -> ans is a reference to an immutable object so when you change the value(from 1234 to 8888), you actually create a new immutable object with a value of 8888 that’s referenced by data. So the original reference ans is still referring to the immutable object 1234 and data will refer to the immutable object 8888.