def find_link(from_group, to_group)
      @links.find do |l|
        /\A#{ from_group }\z/.match(l.from_group) and /\A#{ to_group }\z/.match(l.to_group)
      end
    end
def find_link(from_group, to_group)
      @links.find do |l|
        /\A#{ from_group }\z/.match(l.from_group) and /\A#{ to_group }\z/.match(l.to_group)
      end
    end
Find a link

 @param [String,Symbol] from_group
   the link from_group

 @param [String,Symbol] to_group
   the link to_group

 @return [NilClass,Vic::Highlight]
   the found highlight

 @api private