grp_new()instantiates a newgrpnode.grp_type()checks if the node is agrpnode.grp_<child>_get()returns the<child>node ofgrp.grp_<child>_set()sets the new<child>and deletes the old<child>.grp_<child>_rep()sets the new<child>and returns the old<child>.
Usage
grp_new(ast, lbkt, expr, rbkt)
grp_type(ast, node)
grp_lbkt_get(ast, node)
grp_lbkt_rep(ast, node, lbkt)
grp_lbkt_set(ast, node, lbkt)
grp_expr_get(ast, node)
grp_expr_rep(ast, node, expr)
grp_expr_set(ast, node, expr)
grp_rbkt_get(ast, node)
grp_rbkt_rep(ast, node, rbkt)
grp_rbkt_set(ast, node, rbkt)