Complex Calculator (Python)

import math

def add(x, y):
    return x + y

def subtract(x, y):
    return x - y

def multiply(x, y):
    return x * y

def divide(x, y):
    if y == 0:
        return "Cannot divide by zero!"
    else:
        return x / y

def power(x, y):
    return x ** y

def sqrt(x):
    if x < 0:
        return "Invalid input for square root of a negative number!"
    else:
        return math.sqrt(x)

def logarithm(x, base):
    if x <= 0 or base <= 0 or base == 1:
        return "Invalid input for logarithm!"
    else:
        return math.log(x, base)

print("Select operation:")
print("1. Addition")
print("2. Subtraction")
print("3. Multiplication")
print("4. Division")
print("5. Exponentiation")
print("6. Square Root")
print("7. Logarithm")

while True:
    choice = input("Enter choice (1/2/3/4/5/6/7): ")

    if choice in ('1', '2', '3', '4', '5', '6', '7'):
        if choice in ('1', '2', '3', '4', '5'):
            num1 = float(input("Enter first number: "))
            num2 = float(input("Enter second number: "))

            if choice == '1':
                print("Result:", add(num1, num2))
            elif choice == '2':
                print("Result:", subtract(num1, num2))
            elif choice == '3':
                print("Result:", multiply(num1, num2))
            elif choice == '4':
                print("Result:", divide(num1, num2))
            elif choice == '5':
                print("Result:", power(num1, num2))
        elif choice == '6':
            num = float(input("Enter a number: "))
            print("Result:", sqrt(num))
        elif choice == '7':
            num = float(input("Enter a number: "))
            base = float(input("Enter the base for logarithm: "))
            print("Result:", logarithm(num, base))

        break
    else:
        print("Invalid input. Please enter a valid number (1/2/3/4/5/6/7).")