<div class="btn-group ml-3 mt-3" class="graph_ops">
      <button class="btn btn-outline-secondary dropdown-toggle" type="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" id="load_unload_graph">
      Unloaded graph
      </button>
      <div class="dropdown-menu">
        <a class="dropdown-item" href="#" id="unl_graph" onclick="load_to_unl_parse()">Unloaded graph</a>
        <a class="dropdown-item" href="#" id="load_graph" onclick="unload_to_load_parse()">Loaded graph</a>
      </div>
    </div>

    <div class="btn-group ml-3 mt-3" class="graph_ops">
      <button class="btn btn-outline-secondary dropdown-toggle" type="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" id="dir_undir_graph">
      Undirected graph
      </button>
      <div class="dropdown-menu">
        <a class="dropdown-item" href="#" id="undir_graph" onclick="dir_to_undir_parse()">Undirected graph</a>
        <a class="dropdown-item" href="#" id="dir_graph" onclick="undir_to_dir_parse()">Directed graph</a>
      </div>
    </div>

    <div id="checkbox_multi" class="form-check ml-3 mt-3">
      <input class="form-check-input" type="checkbox" value="" id="check_multi">
      <label class="form-check-label" for="check_multi">
        Multigraph
      </label>
    </div>