Documentation of Range Check seems wrong?

[Ryvian]

Description of the issue

The documentation of Range check says:

Note that <expression> in <range> is equivalent to <expression> = <range>. Both formulas check whether the set of values denoted by <expression> is the same as the set of values denoted by <range>.

But the doc of equality:

For expressions A and B, the formula A = B holds if there is a pair of values—one from A and one from B—that are the same.

So <expression> = <range> means <expression> and <range> have at least one common value, and it does not mean " the set of values denoted by <expression> is the same as the set of values denoted by <range>" as suggested by the documentation of range check.

What exactly does <expr> in <range> and <expr> =<range> mean?