code: function getFieldsModel(text, fieldState) {
  	const model = typeof text === 'object' ? text : parseFields(text);
      let largestIndex = -1;
  
      model.fields.forEach(field => {
  		field.index += fieldState.index;
  		if (field.index > largestIndex) {
  			largestIndex = field.index;
  		}
  	});
  
  	if (largestIndex !== -1) {
  		fieldState.index = largestIndex + 1;
  	}
  
      return model;
  }
docs: Returns fields (tab-stops) model with properly updated indices that won’t
  collide with fields in other nodes of foprmatted tree
  @param  {String|Object} text Text to get fields model from or model itself
  @param  {Object} fieldState Abbreviation tree-wide field state reference
  @return {Object} Field model