Question: I'm trying to do an assignment where I have to find the amount of letters before it gets to a "f" in a string. I was able to get one thing to work, but it only prints out one "f". 

An example of this would be "office", it takes 1 letter to get to one of the "f's", but I can not get it to get to the second f, if that makes sense.

```
a = input()
b = a.index("f")

print(b)

```

Answer: 
I used the following command:

```
docker swarm init --advertise-addr 127.0.0.1

```

It worked just fine.
That error looks two interface IP are running thats way your interface getting ambiguity, And its very simply to execute take your docker-machine's ip then hit,

Ex: docker swarm init --advertise-addr 111.111.11.111