code: function removeDuplicates(data) {
    const dedup = [data[0]];
    for(let i = 1; i < data.length; i++) {
      if (stringify(data[i]) !== stringify(data[i - 1])) {
        dedup.push(data[i]);
      } else {
        dedup.push(undefined);
      }
    }
    return dedup;
  }
docs: To create smaller locale files, we remove duplicated data.
  To be make this work we need to store similar data in arrays, if some value in an array
  is undefined, we can take the previous defined value instead, because it means that it has
  been deduplicated.
  e.g.: [x, y, undefined, z, undefined, undefined]
  The first undefined is equivalent to y, the second and third are equivalent to z
  Note that the first value in an array is always defined.
  
  Also since we need to know which data is assumed similar, it is important that we store those
  similar data in arrays to mark the delimitation between values that have different meanings
  (e.g. months and days).
  
  For further size improvements, "undefined" values will be replaced by a constant in the arrays
  as the last step of the file generation (in generateLocale and generateLocaleExtra).
  e.g.: [x, y, undefined, z, undefined, undefined] will be [x, y, u, z, u, u]