How to concatenate strings for a query to overpass

I would like to write a query that takes the lateral and longitudinal gps coordinates as variables. I have tried it as followed :

lat = 30.74797
long = 53.81236
import overpy
api = overpy.Overpass()

result = api.query("""
way(around:5,""" + lat + """ , """ + long + """)
  ['highway']
  ['highway' !~ 'path']
  ['highway' !~ 'steps'];
(
  ._;
  >;
);
out;""")

Unfortunately it does not work as expected.

How could I manage that ? Thanks