visit_GROUP

# File actionpack/lib/action_dispatch/journey/nfa/builder.rb, line 22
        def visit_GROUP(node)
          from  = @i += 1
          left  = visit(node.left)
          to    = @i += 1

          @tt.accepting = to

          @tt[from, left.first] = nil
          @tt[left.last, to] = nil
          @tt[from, to] = nil

          [from, to]
        end