old_contents: // @flow
  
  /**
   * We want to represent each subs. type as minimally as possible,
   * so instead of using strings we just use characters, which lets us
   * represent 27 individual subs. using a single character each.
   */
  
  export const UserText = 'a';
  export const FullMonth = 'b';
  export const PartialMonth = 'c';
  export const FullYear = 'd';
  export const PartialYear = 'e';
  export const DayOfTheWeek = 'f';
  export const Hour = 'g';
  export const Minutes = 'h';
  export const Seconds = 'i';
  export const PostOrAnteMeridiem = 'j';
  export const Day = 'k';
  
  
  const SubToTypeIdentifierMap: {
    [abbreviation: string]: string
  } = {
    'MMMM': FullMonth,
    'MM': PartialMonth,
    'YYYY': FullYear,
    'YY': PartialYear,
    'dddd': DayOfTheWeek,
    'Do': Day,
    'h': Hour,
    'mm': Minutes,
    'ss': Seconds,
    'a': PostOrAnteMeridiem,
  };
  
  export default SubToTypeIdentifierMap;
new_contents: // @flow
  
  /**
   * We want to represent each subs. type as minimally as possible,
   * so instead of using strings we just use characters, which lets us
   * represent 27 individual subs. using a single character each.
   */
  
  export const UserText = 'a';
  export const FullMonth = 'b';
  export const PartialMonth = 'c';
  export const FullYear = 'd';
  export const PartialYear = 'e';
  export const DayOfTheWeek = 'f';
  export const Hour = 'g';
  export const Minutes = 'h';
  export const Seconds = 'i';
  export const PostOrAnteMeridiem = 'j';
  export const Day = 'k';
  export const DayOfTheMonth = 'i';
  
  
  const SubToTypeIdentifierMap: {
    [abbreviation: string]: string
  } = {
    'MMMM': FullMonth,
    'MM': PartialMonth,
    'YYYY': FullYear,
    'YY': PartialYear,
    'dddd': DayOfTheWeek,
    'DD': DayOfTheMonth,
    'Do': Day,
    'h': Hour,
    'mm': Minutes,
    'ss': Seconds,
    'a': PostOrAnteMeridiem,
  };
  
  export default SubToTypeIdentifierMap;
subject: Add day of the month