System command aliases.
Callable object storing the details of one alias.
Instances are registered as magic functions to allow use of aliases.
Validate the alias, and return the number of arguments.
Define a new alias after validating it.
This will raise an AliasError if there are validation problems.
Return an alias, or None if no alias by that name exists.
Return whether or not a given name has been defined as an alias
Retrieve the command to which an alias expands.
Define an alias, but don’t raise on an AliasError.