-----Description----- 
This task requires writing a Lean 4 method that determines whether a given integer is a power of two.
An integer n is a power of two if there exists an integer x such that n = 2^x.
The method should return true if n is a power of two, and false otherwise.
Note that negative numbers and zero are not powers of two.

-----Input-----
The input consists of one integer:
n: The integer to be tested.

-----Output-----
The output is a boolean:
Returns true if there exists an integer x such that n = 2^x (with n > 0), otherwise false.

