# Virtual Environments

When you work in Python projects you probably should use a **virtual environment** (or a similar mechanism) to isolate the packages you install for each project.

/// info

If you already know about virtual environments, how to create them and use them, you might want to skip this section. 🤓

///

/// tip

A **virtual environment** is different than an **environment variable**.

## Version 4.5.0-RC1

_2020-03-17_

**This release candidate turns on web socket compression.**

The [spec][rfc_7692] includes a sophisticated mechanism for client and server to negotiate
compression features. We strive to offer great performance in our default configuration and so we're
making compression the default for everyone starting with this release candidate.

  // The default if the list is empty is "Persistent", which is the usage defined by the
  // CSI specification and implemented in Kubernetes via the usual PV/PVC mechanism.
  //
  // The other mode is "Ephemeral". In this mode, volumes are defined inline inside the pod spec
  // with CSIVolumeSource and their lifecycle is tied to the lifecycle of that pod.

 *  **Canceling batches of calls is now the application's responsibility.**
    The API to cancel calls by tag has been removed and replaced with a more
    general mechanism. The dispatcher now exposes all in-flight calls via its
    `runningCalls()` and `queuedCalls()` methods. You can write code that
    selects calls by tag, host, or whatever, and invokes `Call.cancel()` on the

  // The default if the list is empty is "Persistent", which is the usage defined by the
  // CSI specification and implemented in Kubernetes via the usual PV/PVC mechanism.
  //
  // The other mode is "Ephemeral". In this mode, volumes are defined inline inside the pod spec
  // with CSIVolumeSource and their lifecycle is tied to the lifecycle of that pod.

//go:cgo_export_dynamic <local> <remote>

	In internal linking mode, put the Go symbol
	named <local> into the program's exported symbol table as
	<remote>, so that C code can refer to it by that name. This
	mechanism makes it possible for C code to call back into Go or
	to share Go's data.

	For compatibility with current versions of SWIG,
	#pragma dynexport is an alias for //go:cgo_export_dynamic.

    HTTPS connection. If you continue to need to connect to webservers
    running SSLv3, you must manually configure your own `ConnectionSpec`.

 *  **OkHttp now offers interceptors.** Interceptors are a powerful mechanism
    that can monitor, rewrite, and retry calls. The [interceptors doc][interceptors] is a full
    introduction to this new API.

 *  New: APIs to iterate and selectively clear the response cache.

		return false
	}

	notInitialized := strings.Contains(err.Error(), "Server not initialized, please try again") ||
		errors.Is(err, errServerNotInitialized)

	// Initializing sub-systems needs a retry mechanism for
	// the following reasons:
	//  - Read quorum is lost just after the initialization
	//    of the object layer.
	//  - Write quorum not met when upgrading configuration

sasl_username    (string)    username for SASL/PLAIN or SASL/SCRAM authentication
sasl_password    (string)    password for SASL/PLAIN or SASL/SCRAM authentication
sasl_mechanism   (string)    sasl authentication mechanism, default 'PLAIN'
tls_client_auth  (string)    clientAuth determines the Kafka server's policy for TLS client auth
sasl             (on|off)    set to 'on' to enable SASL authentication

		kafkaArgs.SASL.User = env.Get(saslUsernameEnv, kv.Get(target.KafkaSASLUsername))
		kafkaArgs.SASL.Password = env.Get(saslPasswordEnv, kv.Get(target.KafkaSASLPassword))
		kafkaArgs.SASL.Mechanism = env.Get(saslMechanismEnv, kv.Get(target.KafkaSASLMechanism))

		if err = kafkaArgs.Validate(); err != nil {
			return nil, err
		}

		kafkaTargets[k] = kafkaArgs
	}

	return kafkaTargets, nil