checkNextIsOperator = function (parent, i) {
  var next = parent.content[i + 1] && parent.content[i + 1].type === 'operator' && parent.content[i + 1].content === ':';
  var spacedNext = parent.content[i + 2] && parent.content[i + 2].type === 'operator' && parent.content[i + 2].content === ':';

  return next || spacedNext;
}
Checks if the next node along is an operator of type ':'

@param {Object} parent - The parent node
@param {number} i - The current child position in the parent node
@returns {boolean} If the sibling node is the correct type of operator