Parser creates and populates a fresh parser.

ClientConfig is the configuration of the Client used by all commands.

ErrExtraArgs is returned if extra arguments to a command are found.

overridden for testing.

Standard streams, redirected for testing.

Key represents a key that can be used for signing assertions.

Notes encapsulate everything that might be interesting about a snap, in order to present a brief summary of it.

SnapAndName holds a snap name and a plug or slot name.

SnapAndNameStrict holds a plug or slot name and, optionally, a snap name.