Can't append data

**What happened (please include outputs or screenshots)**:

I have created a config map via create_namespaced_config_map. I am attempting to patch it by appending existing data. Tried like this

cm = client.V1ConfigMap()
cm.metadata = client.V1ObjectMeta(name=name)
cm.data = cm_data
existingCM = v1.read_namespaced_config_map("test-cm", "test-ns")
print(existingCM)

# print(existingCM)


if existingCM == False:
print(self.v1.read_namespaced_config_map(test-cm", "test-ns"))
self.v1.create_namespaced_config_map(namespace=namespace, body=cm)
print(f"Created ConfigMap {name} in namespace {namespace}")

else:
# print(existingCM)
print(existingCM.update(cm.data))
v1.patch_namespaced_config_map(name=name, namespace=namespace, body=cm)
print(f"Updated ConfigMap {name} in namespace {namespace}")

This wouldn't work. Is there an example that I can follow?

Describe the solution you'd like to see:
Example to achieve successful data append

Start with the create_namespaced_config_map, read_namespaced_config_map, and patch_namespaced_config_map entry points shown in the issue, then review the repository's existing examples for ConfigMap usage. Add a focused example covering creation and appending existing data, and verify that it demonstrates a successful patch.

Written by the indexing model from the issue text.