# File lib/fog/google/requests/storage/head_object.rb, line 27
        def head_object(bucket_name, object_name, options={})
          unless bucket_name
            raise ArgumentError.new('bucket_name is required')
          end
          unless object_name
            raise ArgumentError.new('object_name is required')
          end
          if version_id = options.delete('versionId')
            query = {'versionId' => version_id}
          end
          headers = {}
          headers['If-Modified-Since'] = Fog::Time.at(options['If-Modified-Since'].to_i).to_date_header if options['If-Modified-Since']
          headers['If-Unmodified-Since'] = Fog::Time.at(options['If-Unmodified-Since'].to_i).to_date_header if options['If-Modified-Since']
          headers.merge!(options)
          request({
            :expects  => 200,
            :headers  => headers,
            :host     => "#{bucket_name}.#{@host}",
            :method   => 'HEAD',
            :path     => CGI.escape(object_name),
            :query    => query
          })
        end