# Create a new User object bound to the receiver and add it to the list\r
# of <code>User</code>s on the receiver, unless the User was present\r
# already. In this case, the default action is to raise an exception,\r
# Create a new User object bound to the receiver and add it to the list\r
# of <code>User</code>s on the receiver, unless the User was present\r
# already. In this case, the default action is to raise an exception,\r