convertEdge = function (dotEdge) {
      var graphEdge = {
        from: dotEdge.from,
        to: dotEdge.to,
      };
      merge(graphEdge, convertAttr(dotEdge.attr, EDGE_ATTR_MAPPING));

      // Add arrows attribute to default styled arrow.
      // The reason why default style is not added in parseAttributeList() is
      // because only default is cleared before here.
      if (graphEdge.arrows == null && dotEdge.type === "->") {
        graphEdge.arrows = "to";
      }

      return graphEdge;
    }
Convert an edge in DOT format to an edge with VisGraph format
@param {object} dotEdge
@returns {object} graphEdge