docs: def check_flavors(session):
      """Build the flavors mapping
  
      returns the mappings id <-> flavor
      """
      nclient = nova.Client(NOVA_VERSION, session=session,
                            region_name=os.environ['OS_REGION_NAME'])
      flavors = nclient.flavors.list()
      to_id = dict(list(map(lambda n: [n.name, n.id], flavors)))
      to_flavor = dict(list(map(lambda n: [n.id, n.name], flavors)))
      return to_id, to_flavor