Called by pyang plugin framework at to initialize the plugin.

def pyang_plugin_init():
    """Called by pyang plugin framework at to initialize the plugin."""

    # Register the plugin
    plugin.register_plugin(RESTCONFPlugin())

    # Register that we handle extensions from the YANG module 'ietf-restconf'
    grammar.register_extension_module(restconf_module_name)

    yd = (restconf_module_name, 'yang-data')
    statements.add_data_keyword(yd)
    statements.add_keyword_with_children(yd)
    statements.add_keywords_with_no_explicit_config(yd)

    # Register the special grammar
    for (stmt, occurance, (arg, rules), add_to_stmts) in restconf_stmts:
        grammar.add_stmt((restconf_module_name, stmt), (arg, rules))
        grammar.add_to_stmts_rules(add_to_stmts,
                                   [((restconf_module_name, stmt), occurance)])

    # Add validation functions
    statements.add_validation_fun('expand_2',
                                  [yd],
                                  v_yang_data)

    # Register special error codes
    error.add_error_code('RESTCONF_YANG_DATA_CHILD', 1,
                         "the 'yang-data' extension must have exactly one " +
                         "child that is a container")