Currently undef is returned in this situation. Attributes If nodes are objects, then attributes are a node's instance variables. The main difference one will notice is cosmetic. Again, these two expressions mean the same thing. An aggregate of one is interpreted just as if it were a single value.
Aggregates become useful when attributes needs to have a list of values.
There are accessors for attributes that work like your typical perl getters and setters. That is, when called without a parameter, the method behaves as a getter. When called with a parameter, the method behaves as a setter and the value of the parameter is assigned to the attribute. These are accessors for attributes that are typically single-valued. This is the name of the node.