How do you work with sass in bootstrap?

Question

Sass

In the docks, all the code is in scss.
Now I'm trying to change the breakpoint, but some kind of incomprehensible error appears (maybe I'm stupid).
The code:

$grid-breakpoints: (
  xs: 0,
  sm: 576px,
  md: 768px,
  lg: 992px,
  xl: 1200px
) !default;


@import '../libs/bootstrap/scss/bootstrap.scss'

Error text: app\sass\custom.sass
Error: unclosed parenthesis
on line 1 of app/sass/custom.sass
>> $grid-breakpoints: ( {
---------------- ---^
But as you can see, there is no parenthesis there.