# File lib/mongo/grid/file/info.rb, line 136
        def initialize(document)
          @client_md5 = Digest::MD5.new unless document[:disable_md5] == true
          # document contains a mix of user options and keys added
          # internally by the driver, like session.
          # Remove the keys that driver adds but keep user options.
          document = document.reject do |key, value|
            key.to_s == 'session'
          end
          @document = default_document.merge(Options::Mapper.transform(document, MAPPINGS))
        end