let score = 85

if score >= 90 {
  "A"
} else if score >= 80 {
  "B" 
} else if score >= 70 {
  "C"
} else {
  "F"
}

let weather = "sunny"
if weather == "sunny" {
  "Go outside!"
} else {
  "Stay inside"
}

let x = 0
if x == 0 {
  "zero"
} else if x > 0 {
  "positive"
} else {
  "negative" 
}

let age = 25
if age >= 18 && age < 65 {
  "adult"
} else {
  "not adult"
}

true && false || true