how to use when statement in kotlin code example

Example 1: kotlin when

fun numberTypeName(x: Number) = when(x) {
 0 -> "Zero" // Equality check
 in 1..4 -> "Four or less" // Range check
 5, 6, 7 -> "Five to seven" // Multiple values
 is Byte -> "Byte" // Type check
 else -> "Some number"
}

Example 2: kotlin when

fun signAsString(x: Int)= when {
 x < 0 -> "Negative"
 x == 0 -> "Zero"
 else -> "Positive"
}