Debug creates an Option to set the debug flag to b.

Memoize creates an Option to set the memoize flag to b.

Parse parses the data from b using filename as information in the error messages.

ParseFile parses the file identified by filename.

ParseReader parses the data from r using filename as information in the error messages.

Recover creates an Option to set the recover flag to b.

Checks the paramters 1.

Means a property of agent and target may not be same.

Means a property of agent and target must be same.

The relation is unknown.

The filter of node.

The filter of node.

The parameters for query.

Defines the IR for relation of hosts(between agent and target).

Option is a function that can set an option on the parser.