--- /dev/null
+# http\Env\Response http\Env\Response::setEtag(string $etag)
+
+Set a custom ETag.
+
+> **Note:** This will be used for caching and pre-condition checks.
+
+## Params:
+
+* string $etag
+ A ETag.
+
+## Returns:
+
+* http\Env\Response, self.