code: function encode(utm, accuracy) {
    // prepend with leading zeroes
    const seasting = '00000' + utm.easting,
      snorthing = '00000' + utm.northing;
  
    return utm.zoneNumber + utm.zoneLetter + get100kID(utm.easting, utm.northing, utm.zoneNumber) + seasting.substr(seasting.length - 5, accuracy) + snorthing.substr(snorthing.length - 5, accuracy);
  }
docs: Encodes a UTM location as MGRS string.
  
  @private
  @param {object} utm An object literal with easting, northing,
  zoneLetter, zoneNumber
  @param {number} accuracy Accuracy in digits (1-5).
  @return {string} MGRS string for the given UTM location.