def factorial(x: int)-> int:
    """
    This function returns the `Factorial` value of a number which is specified in the function by user.
    
    This function takes exactly one argument.
    Args:
    `x: int` : x should be an `integer number` for calculating the factorial value of x.
    """
    
    fact = 1
    for i in range(1, x+1):
        fact*=i

    return fact