getMonthName (month, months) {
    if (!months) {
      throw Error('missing 2nd parameter Months array')
    }
    if (typeof month === 'object') {
      return months[this.getMonth(month)]
    }
    if (typeof month === 'number') {
      return months[month]
    }
    throw TypeError('Invalid type')
  }
Return name of the month
@param {Number|Date}
@param {Array}
@return {String}