private void Remove(ICommandManager commandManager, IPlugin plugin, String name, ushort arity)
{
QualifiedNameTypes qualifiedName = QualifiedAliasName(plugin.Name, name, arity);
if(!_aliases.ContainsKey(qualifiedName) || !_commands.ContainsKey(qualifiedName))
throw new InvalidOperationException("Alias with name " + name + " and arity " + arity
+ " does not exist.");
AliasData alias = _aliases[qualifiedName];
AliasCommand command = _commands[qualifiedName];
commandManager.Remove(command);
_unqualifiedAliases.Remove(name, arity);
_commands.Remove(qualifiedName);
_aliases.Remove(qualifiedName);
Aliases.Remove(alias);
}