addTogether(2, 3)
should return 5.
addTogether(23, 30)
should return 53.
addTogether(5)(7)
should return 12.
addTogether("https://www.youtube.com/watch?v=dQw4w9WgXcQ")
should return undefined
.
addTogether(2, "3")
should return undefined
.
addTogether(2)([3])
should return undefined
.