takeIf

Returns this value if it satisfies the given predicate or null, if it doesn't.

inline fun <T> T.takeIf(predicate: (T) -> Boolean): T?(source)

val number = 10

val evenNumber = number.takeIf { it % 2 == 0 }   // returns 10
val oddNumber  = number.takeIf { it % 2 != 0 }   // returns null

println("evenNumber = $evenNumber")  // evenNumber = 10
println("oddNumber  = $oddNumber")   // oddNumber  = null

Source