text: /** @file Functions to work with Instrument instances */
  
  /**
   * Functions to extract information from Instrument instances
   *
   * @namespace
   * @name      instrumentFunctions
   * @memberof  module:core.logic
   */
  module.exports = () => {
      /**
       * Toggles playback of the note of the given instrument
       *
       * @memberof module:core.logic.instrumentFunctions
       *
       * @param {module:core.models.Instrument} instrument The instrument to update
       * @param {Number}                        position   The note to toggle
       *
       * @return {module:core.models.Instrument} A copy of the instrument with the toggled note
       */
      const toggleNote = (instrument, position) => instrument.set(
          'notes',
          instrument.notes[instrument.notes.has(position) ? 'delete' : 'add'](position)
      );
  
      return { toggleNote };
  };
  