Replace different ways of checking emptiness of collections and options with .isEmpty, .nonEmpty or .isDefined.

!seq.isEmpty -> seq.nonEmpty

seq.size == 0 -> seq.isEmpty

seq.size != 0 -> seq.nonEmpty

!(seq.length > 1) -> seq.isEmpty

seq.exists(_ => true) -> seq.nonEmpty

seq.exists(const(true)) -> seq.nonEmpty

!option.isEmpty -> option.isDefined

option == None -> option.isEmpty

option != None -> option.isDefined