code: def resolve_indirect (data, key, splithosts=False):
      
      value = data[key]
      env_value = os.environ.get(value)
      if env_value:
          if splithosts:
              data[key] = split_hosts(env_value)
          else:
              data[key] = env_value
      else:
          del data[key]
docs: Replace name of environment variable with its value.