Solves @Casidoos 11-23-2020 challenge: find if an integer has a square root

cassidoo_sqrt_solver_11-23-20.py

def is_square(n, upper, lower=0):
    #edge case
    if n == 1:
        return True

    #if exhausted all possibilities
    if upper - lower < 2 and lower**2 != n and upper != n:
        return False
    guess = ((upper - lower) // 2) + lower
    guess_square = guess ** 2
    if guess_square == n:
        return True

    #recurse on lower half
    elif guess_square > n:
        return is_square(n, upper=guess, lower=lower)

    #recurse on higher half
    elif guess_square < n:
        return is_square(n, upper=upper, lower=guess)