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: 
It looks like you have two active network interfaces, one on `enp1s0` and another on `wlp2s0`. I'd guess `enp1s0` is an Ethernet connection and `wlp2s0` is a WiFi connection.

As mentioned in the question you linked to, if you have multiple addresses on different interfaces, you have to specify one with `--advertise-addr`. In your case, you're essentially choosing between your Ethernet and WiFi interfaces.
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