GitBook: [#206] deep update example

operators/keys.md

@@ -0,0 +1,47 @@
+# Keys
+
+Use the `keys` operator to return map keys or array indices.
+
+## Map keys
+
+Given a sample.yml file of:
+
+```yaml
+dog: woof
+cat: meow
+```
+
+then
+
+```bash
+yq eval 'keys' sample.yml
+```
+
+will output
+
+```yaml
+- dog
+- cat
+```
+
+## Array keys
+
+Given a sample.yml file of:
+
+```yaml
+- apple
+- banana
+```
+
+then
+
+```bash
+yq eval 'keys' sample.yml
+```
+
+will output
+
+```yaml
+- 0
+- 1
+```