Determine if a number is a power of two.

A number is a power of two if and only if it has exactly one bit set to 1 in its binary representation. A common and efficient way to check this is using the bitwise AND operation: n & (n - 1). If n is a power of two (and n > 0), this operation will result in 0. For example, if n = 8 (binary 1000), then n - 1 = 7 (binary 0111). 8 & 7 is 0. If n = 6 (binary 0110), then n - 1 = 5 (binary 0101). 6 & 5 is 0100, which is not 0.