TODO: https://github.com/xmidt-org/ears/issues/74.

Error wraps a plugin's errors.

HasherMock is a mock implementation of Hasher.

InvalidConfigError is returned when a configuration parameter results in a plugin error.

NewPluginererMock is a mock implementation of NewPluginerer.

NotSupportedError can be returned if a plugin doesn't support publishing subscribing.

Plugin implements Pluginer.

PluginerMock is a mock implementation of Pluginer.

Hasher defines the hashing interface that a pluginer needs to implement.

NewPluginerer is something that is able to return a new Pluginer.

Pluginer defines values that should be returned in order to get visibility into which plugin was loaded and how it was configured.

ErrorCode holds a numeric value that can be used to communicate an enumerated list of error codes back to the caller.