pc = 0
registers[code[pc]['register1']]

labels[code[pc]['labeldef']]

class Rational:

    def __init__(self,n,d):
        self.numerator = n
        self.denominator = d
        self.reduce()

    def add(self,r):
        num = self.numerator * r.denominator + self.deniminator * r.numerator
        den = self.denominator * r.denominator
        return Rational(num,den)
    
    # please write mul, div, minus methods

    @staticmethod
    def gcd(m,n): # assume m >= n
        while n != 0:
            r = m%n
            m = n
            n = r
        return m

    def reduce(self):
        #if self.numerator > self.denominator:
        #    g = gcd(self.numerator,self.denominator)
        #else:
        #    g = gcd(self.denominator,self.numerator)
        g = Rational.gcd(self.numerator,self.denominator)
        if g == 0:
            return None
        elif self.numerator < 0 and self.denominator < 0:
            self.numerator = -self.numerator / g
            self.denominator = -self.denominator / g
        elif ... + num, - den
        elif ... -num, + den
        else: +num, +den 


    def __str__(self):  # should return string version of the object
        return str(self.numerator) + " / " + str(self.denominator)

r1 = Rational(18,12)
r2 = Rational(15,6)
r3 = r1.add(r2)
...
...
print(r3)

code = [ {'labeldef': 'N0', 'opcode': 'CJMP', 'register1': 'R2', 'jmplabel': 'N1'}, 
         {'opcode': 'INC', 'register1': 'R1'}, 
         {'opcode': 'DEC', 'register1': 'R2'}, 
         {'opcode': 'UJMP', 'jmplabel': 'N0'}, 
         {'labeldef': 'N1', 'opcode': 'CONTINUE'}
       ]

def construct_labels_from_code(code):
    labels = {}
    for ino,ins in enumerate(code):
        if "labeldef" in ins:
            labels[ins["labeldef"]] = ino
    return labels

construct_labels_from_code(code)

{'N0': 0, 'N1': 4}