Why is it that the input ab is the same thing twice

Question

import random

input = str(input(""))
key = random.randint(123, 9999999)

def encode(v):
v = v * key
v =+ key
v = str(v)
v = v + ' '
return(v)

a = encode(1)
b = encode(2)
c = encode(3)
d = encode(4)

output = input.replace("a", a).replace("b", b)
print(output)

Answer 1

You overwrite v with the constant value of key instead of adding it:
v += key

Random key with seed within the function helps too...