def __init__(self, *, credentials: Optional[ga_credentials.Credentials]=None, transport: Union[(str, FeedServiceTransport, None)]=None, client_options: Optional[client_options_lib.ClientOptions]=None, client_info: gapic_v1.client_info.ClientInfo=DEFAULT_CLIENT_INFO) -> None:
    'Instantiates the feed service client.\n\n        Args:\n            credentials (Optional[google.auth.credentials.Credentials]): The\n                authorization credentials to attach to requests. These\n                credentials identify the application to the service; if none\n                are specified, the client will attempt to ascertain the\n                credentials from the environment.\n            transport (Union[str, FeedServiceTransport]): The\n                transport to use. If set to None, a transport is chosen\n                automatically.\n            client_options (google.api_core.client_options.ClientOptions): Custom options for the\n                client. It won\'t take effect if a ``transport`` instance is provided.\n                (1) The ``api_endpoint`` property can be used to override the\n                default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT\n                environment variable can also be used to override the endpoint:\n                "always" (always use the default mTLS endpoint), "never" (always\n                use the default regular endpoint) and "auto" (auto switch to the\n                default mTLS endpoint if client certificate is present, this is\n                the default value). However, the ``api_endpoint`` property takes\n                precedence if provided.\n                (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable\n                is "true", then the ``client_cert_source`` property can be used\n                to provide client certificate for mutual TLS transport. If\n                not provided, the default SSL client certificate will be used if\n                present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not\n                set, no client certificate will be used.\n            client_info (google.api_core.gapic_v1.client_info.ClientInfo):\n                The client info used to send a user-agent string along with\n                API requests. If ``None``, then default info will be used.\n                Generally, you only need to set this if you\'re developing\n                your own client library.\n\n        Raises:\n            google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport\n                creation failed for any reason.\n        '
    if isinstance(client_options, dict):
        client_options = client_options_lib.from_dict(client_options)
    if (client_options is None):
        client_options = client_options_lib.ClientOptions()
    if (os.getenv('GOOGLE_API_USE_CLIENT_CERTIFICATE', 'false') not in ('true', 'false')):
        raise ValueError('Environment variable `GOOGLE_API_USE_CLIENT_CERTIFICATE` must be either `true` or `false`')
    use_client_cert = (os.getenv('GOOGLE_API_USE_CLIENT_CERTIFICATE', 'false') == 'true')
    client_cert_source_func = None
    is_mtls = False
    if use_client_cert:
        if client_options.client_cert_source:
            is_mtls = True
            client_cert_source_func = client_options.client_cert_source
        else:
            is_mtls = mtls.has_default_client_cert_source()
            if is_mtls:
                client_cert_source_func = mtls.default_client_cert_source()
            else:
                client_cert_source_func = None
    if (client_options.api_endpoint is not None):
        api_endpoint = client_options.api_endpoint
    else:
        use_mtls_env = os.getenv('GOOGLE_API_USE_MTLS_ENDPOINT', 'auto')
        if (use_mtls_env == 'never'):
            api_endpoint = self.DEFAULT_ENDPOINT
        elif (use_mtls_env == 'always'):
            api_endpoint = self.DEFAULT_MTLS_ENDPOINT
        elif (use_mtls_env == 'auto'):
            api_endpoint = (self.DEFAULT_MTLS_ENDPOINT if is_mtls else self.DEFAULT_ENDPOINT)
        else:
            raise MutualTLSChannelError('Unsupported GOOGLE_API_USE_MTLS_ENDPOINT value. Accepted values: never, auto, always')
    if isinstance(transport, FeedServiceTransport):
        if (credentials or client_options.credentials_file):
            raise ValueError('When providing a transport instance, provide its credentials directly.')
        if client_options.scopes:
            raise ValueError('When providing a transport instance, provide its scopes directly.')
        self._transport = transport
    else:
        Transport = type(self).get_transport_class(transport)
        self._transport = Transport(credentials=credentials, credentials_file=client_options.credentials_file, host=api_endpoint, scopes=client_options.scopes, client_cert_source_for_mtls=client_cert_source_func, quota_project_id=client_options.quota_project_id, client_info=client_info, always_use_jwt_access=True)
Instantiates the feed service client.

Args:
    credentials (Optional[google.auth.credentials.Credentials]): The
        authorization credentials to attach to requests. These
        credentials identify the application to the service; if none
        are specified, the client will attempt to ascertain the
        credentials from the environment.
    transport (Union[str, FeedServiceTransport]): The
        transport to use. If set to None, a transport is chosen
        automatically.
    client_options (google.api_core.client_options.ClientOptions): Custom options for the
        client. It won't take effect if a ``transport`` instance is provided.
        (1) The ``api_endpoint`` property can be used to override the
        default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT
        environment variable can also be used to override the endpoint:
        "always" (always use the default mTLS endpoint), "never" (always
        use the default regular endpoint) and "auto" (auto switch to the
        default mTLS endpoint if client certificate is present, this is
        the default value). However, the ``api_endpoint`` property takes
        precedence if provided.
        (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable
        is "true", then the ``client_cert_source`` property can be used
        to provide client certificate for mutual TLS transport. If
        not provided, the default SSL client certificate will be used if
        present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not
        set, no client certificate will be used.
    client_info (google.api_core.gapic_v1.client_info.ClientInfo):
        The client info used to send a user-agent string along with
        API requests. If ``None``, then default info will be used.
        Generally, you only need to set this if you're developing
        your own client library.

Raises:
    google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
        creation failed for any reason.
def __init__(self, *, credentials: Optional[ga_credentials.Credentials]=None, transport: Union[(str, FeedServiceTransport, None)]=None, client_options: Optional[client_options_lib.ClientOptions]=None, client_info: gapic_v1.client_info.ClientInfo=DEFAULT_CLIENT_INFO) -> None:
    'Instantiates the feed service client.\n\n        Args:\n            credentials (Optional[google.auth.credentials.Credentials]): The\n                authorization credentials to attach to requests. These\n                credentials identify the application to the service; if none\n                are specified, the client will attempt to ascertain the\n                credentials from the environment.\n            transport (Union[str, FeedServiceTransport]): The\n                transport to use. If set to None, a transport is chosen\n                automatically.\n            client_options (google.api_core.client_options.ClientOptions): Custom options for the\n                client. It won\'t take effect if a ``transport`` instance is provided.\n                (1) The ``api_endpoint`` property can be used to override the\n                default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT\n                environment variable can also be used to override the endpoint:\n                "always" (always use the default mTLS endpoint), "never" (always\n                use the default regular endpoint) and "auto" (auto switch to the\n                default mTLS endpoint if client certificate is present, this is\n                the default value). However, the ``api_endpoint`` property takes\n                precedence if provided.\n                (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable\n                is "true", then the ``client_cert_source`` property can be used\n                to provide client certificate for mutual TLS transport. If\n                not provided, the default SSL client certificate will be used if\n                present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not\n                set, no client certificate will be used.\n            client_info (google.api_core.gapic_v1.client_info.ClientInfo):\n                The client info used to send a user-agent string along with\n                API requests. If ``None``, then default info will be used.\n                Generally, you only need to set this if you\'re developing\n                your own client library.\n\n        Raises:\n            google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport\n                creation failed for any reason.\n        '
    if isinstance(client_options, dict):
        client_options = client_options_lib.from_dict(client_options)
    if (client_options is None):
        client_options = client_options_lib.ClientOptions()
    if (os.getenv('GOOGLE_API_USE_CLIENT_CERTIFICATE', 'false') not in ('true', 'false')):
        raise ValueError('Environment variable `GOOGLE_API_USE_CLIENT_CERTIFICATE` must be either `true` or `false`')
    use_client_cert = (os.getenv('GOOGLE_API_USE_CLIENT_CERTIFICATE', 'false') == 'true')
    client_cert_source_func = None
    is_mtls = False
    if use_client_cert:
        if client_options.client_cert_source:
            is_mtls = True
            client_cert_source_func = client_options.client_cert_source
        else:
            is_mtls = mtls.has_default_client_cert_source()
            if is_mtls:
                client_cert_source_func = mtls.default_client_cert_source()
            else:
                client_cert_source_func = None
    if (client_options.api_endpoint is not None):
        api_endpoint = client_options.api_endpoint
    else:
        use_mtls_env = os.getenv('GOOGLE_API_USE_MTLS_ENDPOINT', 'auto')
        if (use_mtls_env == 'never'):
            api_endpoint = self.DEFAULT_ENDPOINT
        elif (use_mtls_env == 'always'):
            api_endpoint = self.DEFAULT_MTLS_ENDPOINT
        elif (use_mtls_env == 'auto'):
            api_endpoint = (self.DEFAULT_MTLS_ENDPOINT if is_mtls else self.DEFAULT_ENDPOINT)
        else:
            raise MutualTLSChannelError('Unsupported GOOGLE_API_USE_MTLS_ENDPOINT value. Accepted values: never, auto, always')
    if isinstance(transport, FeedServiceTransport):
        if (credentials or client_options.credentials_file):
            raise ValueError('When providing a transport instance, provide its credentials directly.')
        if client_options.scopes:
            raise ValueError('When providing a transport instance, provide its scopes directly.')
        self._transport = transport
    else:
        Transport = type(self).get_transport_class(transport)
        self._transport = Transport(credentials=credentials, credentials_file=client_options.credentials_file, host=api_endpoint, scopes=client_options.scopes, client_cert_source_for_mtls=client_cert_source_func, quota_project_id=client_options.quota_project_id, client_info=client_info, always_use_jwt_access=True)