Błąd wcięcia Python

from flask import flask
from redis import Redis, RedisError
import os
import socket

redis = Redis(host="redis", db=0, socket_connnect_timeout=2, socket_timeout=2)

app=Flask(__name__)
@app.route("/")
def hello():

try:
    visits = redis.incr("counter")
except RedisError:
    visits="<i>Cannot connect to Redis, counter disabled</i>"

html="<h3> Hello {name}!</h3>"\
    "<b>Hostname:</b> {hostname}<br/>"
    "<b>Visits:</b> {visits}"
returnhtml.format(name=os.getenv("NAME", "world"), hostname=socket.gethostname(), visits=visits)

if __name__ =="__main__":
    app.run(host='0.0.0.0', port=80)
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