Mutating vs Rebinding the Default

Two helpers, each with a list default:

def accumulate(x, bucket=[]):
    bucket.append(x)
    return bucket

def replace(x, bucket=[]):
    bucket = bucket + [x]
    return bucket

print(accumulate(1))
print(accumulate(2))
print(replace(1))
print(replace(2))

What gets printed, in order?