code: function combineNumeratorsAboveCommonDenominator(node) {
    let newNode = clone(node);
  
    const commonDenominator = newNode.args[0].args[1];
    const numeratorArgs = [];
    newNode.args.forEach(fraction => {
      numeratorArgs.push(fraction.args[0]);
    });
    const newNumerator = Node.Creator.parenthesis(
      Node.Creator.operator('+', numeratorArgs));
  
    newNode = Node.Creator.operator('/', [newNumerator, commonDenominator]);
    return Node.Status.nodeChanged(
      ChangeTypes.COMBINE_NUMERATORS, node, newNode);
  }
docs: Given a + operation node with a list of fraction nodes as args that all have the same denominator, add them together. e.g. 2/3 + 5/3 -> (2+5)/3 Returns the new node.