What is the use cases of Ignored Variable syntax in Scala?

Question

According to this answer https://stackoverflow.com/a/8001065/1586965 we can do this in Scala:

val _ = 5

Now I understand the point of ignor

Answer 1

The other use case (that I can think of) is related to extraction (and is called out under "Wildcard patterns" in the linked answer):

val getCartesianPoint = () => (1, 2, 3)
// We don't care about the z axis, so we assign it to _
val (x, y, _) = getCartesianPoint()

val regex = "(.*?)|(.*?)|?.*".r
// Really, any unapply or unapplySeq example will do
val regex(_, secondValue) = "some|delimited|value|set"