# File lib/mongo/collection.rb, line 983
    def normalize_hint_fields(hint)
      case hint
      when String
        {hint => 1}
      when Hash
        hint
      when nil
        nil
      else
        h = BSON::OrderedHash.new
        hint.to_a.each { |k| h[k] = 1 }
        h
      end
    end