I've always wanted to write this but having problems

[357mag]

I've wanted to write a program that converts an integer to it's binary equivalent. I'm getting an error saying Unbound Local Error. Local variable binary_string referenced before assignment. The last line in the while loop before the return statement is being flagged an error. I probably have other things wrong too if you see them please let me know.

I'm rather lost:

def main():
    x = int(input("Enter an integer: "))
    binary_string = ""
    binary_string = decimal_to_binary(x)
    
def decimal_to_binary(n): 
    
    while(n > 0):
        remainder = n % 2
        n = n / 2
        binary_string = str(remainder) + binary_string
        
    return binary_string

main()