# File lib/mongo/util/conversions.rb, line 102
    def sort_value(value)
      val = value.to_s.downcase
      return 1 if ASCENDING_CONVERSION.include?(val)
      return -1 if DESCENDING_CONVERSION.include?(val)
      raise InvalidSortValueError.new(
        "#{self} was supplied as a sort direction when acceptable values are: " +
        "Mongo::ASCENDING, 'ascending', 'asc', :ascending, :asc, 1, Mongo::DESCENDING, " +
        "'descending', 'desc', :descending, :desc, -1.")
    end