[kotlin] infix function

코틀린에서는 두 개의 객체 중간에 들어가게 되는 함수 형태를 Infix Function 이라고 부른다.

 

https://velog.io/@haero_kim/Kotlin-Infix-Function-%EC%9D%B4-%EB%AD%90%EA%B2%8C