In Go, not is represented by the exclamation mark (!) and it is used to invert a boolean value. For example, if a boolean expression is true, applying not to it will result in false, and vice versa. Here are some examples:
a := true
b := !a
fmt.Println(a) // true
fmt.Println(b) // false
In this example, a is assigned a value of true, and b is assigned the inverse of a, which is false.
x := 5
y := 10
fmt.Println(x != y) // true
fmt.Println(!(x != y)) // false
In this example, the expression x != y evaluates to true because 5 is not equal to 10. Applying not to this expression using ! results in false.
z := "hello"
fmt.Println(!z) // invalid operation: !z (operator ! not defined on string)
In this example, not cannot be applied to the string value z because not is only defined for boolean values. This produces a compile-time error.