def find_seperation(arg):
    """
    Helper Function for decompose
    
    @param: arg is a string corresponding to two function statement sepereated by a comma
            Example: "and(and(a,c),b),or(ab,b)"
    @return:
        return the index of the comma seperating the functions or -1 if no such comma exist
    """
    open_parenthesis = 0 
    for i in range(len(arg)):
        if arg[i] == '(':
            open_parenthesis += 1
        elif arg[i] == ')':
            open_parenthesis -= 1
        elif arg[i] == ',' and open_parenthesis == 0:
            return i
    return -1