"hello".len()
"world".upper()
"TEST".lower()
"  whitespace  ".trim()

"hello" + " " + "world"
"test".replace("e", "a")

"one,two,three".split(",")
"a-b-c-d".split("-")

let sentence = "The quick brown fox"
sentence.len()
sentence.upper()
sentence.split(" ")

"".len()
" ".trim()
"single".replace("x", "y")