"Selector Interpolation with Extend" possibly contains outdated info (doc states not supported, but works)

https://lesscss.org/features/#extend-feature-selector-interpolation-with-extend
The section opens with the example:

Selector with variable will not be matched:

@variable: .bucket;
@{variable} { // interpolated selector
  color: blue;
}
.some-class:extend(.bucket) {} // does nothing, no match is found

However, this does seem to work (at least since LESS v4.1.0):

@selector: e('.example');
@{selector} {  content: 'testing :extend ONTO interpolated selector';  }

.test-1:extend( @{selector} ) {  content: 'doesnt work, as expected';  }
.test-2:extend( .example ) {  content: 'does work, contrary to doc';  }

Start with the linked Selector Interpolation with Extend section and reproduce both examples using LESS v4.1.0 or the current version. Compare the documented behavior with the results, then update the section so its explanation and examples accurately describe interpolation and :extend; done means the documentation matches a verified test case.