a confusing case in selection or collapsed selection

[acumen1005]

I'm confused by this example. Consider the following Slate document

[{text: 'one '}, {text: 'two', bold: true}, {text: ' three'}]

It would render like so:

one two three

Now if we selected the "two":

one |two| three

Then move the focus handle to left until they(anchor and focus) collapse, like:

one |two three

Now the selection is:

{
  anchor: { path: [1], offset: 0 },
  focus: { path: [0], offset: 5 }
}

My confusion arises in how to determine if the selection has collapsed, given that the anchor and focus in the above selection do not definitely match.