Attributes are ways to shape process execution and additional information that alters the environment the process executes in.

Core specifies the interface to a process controlled by iptb.

Metrics are ways to gather information during process execution.

Output manages running, inprocess, a process.

GetAttrDescFunc returns the description of the attribute `attr`.

GetAttrListFunc returns a list of attribute names that can be queried from the node.

NewNodeFunc constructs a node implementing the Core interface.