code: function removeMultiplicationByOne(node) {
    if (node.op !== '*') {
      return Node.Status.noChange(node);
    }
    const oneIndex = node.args.findIndex(arg => {
      return Node.Type.isConstant(arg) && arg.value === '1';
    });
    if (oneIndex >= 0) {
      let newNode = clone(node);
      // remove the 1 node
      newNode.args.splice(oneIndex, 1);
      // if there's only one operand left, there's nothing left to multiply it
      // to, so move it up the tree
      if (newNode.args.length === 1) {
        newNode = newNode.args[0];
      }
      return Node.Status.nodeChanged(
        ChangeTypes.REMOVE_MULTIPLYING_BY_ONE, node, newNode);
    }
    return Node.Status.noChange(node);
  }
docs: If `node` is a multiplication node with 1 as one of its operands, remove 1 from the operands list. Returns a Node.Status object.