Power of Two

The Bit Check guards the gate of the Binary Keep. Every visitor is a number, and the gate opens only for powers of two: 1, 2, 4, 8, 16, … (2^k for some k >= 0). Zero and negative numbers never get in.

Write is_power_of_two(n: int) -> bool that says whether the gate opens for n.

is_power_of_two(64)      # True   (1000000 in binary)
is_power_of_two(72)      # False  (1001000)
is_power_of_two(1)       # True   (2^0)
is_power_of_two(0)       # False
is_power_of_two(-8)      # False

Constraints:

• -2^31 <= n <= 2^31 - 1.

Dividing by two in a loop works, but there's a one-line answer with no loop at all. Aim for O(1).