Definitely less elegant than other solutions, but for my fellow beginners:

def flippingBits(n):

        # turn 'n' into binary string
        l=format(n, '032b')
        m=[]

        # flip all bits
        for i in range(len(l)):
                m.append(1-int(l[i]))

        num=0
        if m[-1]==1:
                num+=1
        for i in range(len(m)-1):

                # start from the back of the string, skip m [ -1 ]
                curr=int(m[-i-2])
                num+=(2*curr)**(i+1)
        return(num)