code: def _download_cl(cls, filename):
          
          file_info = cls.parse_remote(filename)
          region = cls.get_region(filename)
          if region in REGIONS_NEWPERMS["s3"]:
              return cls._cl_aws_cli(file_info, region)
          else:
              return cls._cl_gof3r(file_info, region)
docs: Provide potentially streaming download from S3 using gof3r
          or the AWS CLI.
  
          Selects the correct endpoint for non us-east support:
              http://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
  
          In eu-central-1 gof3r does not support new AWS signatures,
          so we fall back to the standard AWS commandline interface:
              https://github.com/rlmcpherson/s3gof3r/issues/45