def add(entry)
      return import_hash(entry) if entry.is_a?(Hash)
      return import_array(entry) if entry.is_a?(Array)

      raise ArgumentError, 'Must be a hash or an array of hashes'
    end
def add(entry)
      return import_hash(entry) if entry.is_a?(Hash)
      return import_array(entry) if entry.is_a?(Array)

      raise ArgumentError, 'Must be a hash or an array of hashes'
    end
add new entries to po file

 @example
   entry = {
             translator_comment: 'comment',
             reference: 'reference comment',
             flag: 'fuzzy',
             msgid: 'translatable string',
             msgstr: 'translation'
           }
   add(entry)

 @param entry [Hash, Array] a hash of entry contents or an array of hashes
 @return [Po]