chore: add language identifiers

src/content/docs/apm/agents/python-agent/python-agent-api/addcustomattributes-python-agent-api.mdx

@@ -11,7 +11,7 @@ metaDescription: 'Python API: This call adds a custom attribute (key/value tuple
 
 ## Syntax
 
-```
+```py
 newrelic.agent.add_custom_attributes(items)
 ```
 
@@ -51,7 +51,7 @@ Attributes may be found in APM if the transaction is associated with an error or
       </td>
 
       <td>
-        Required. Each item in the list must be a tuple, with the first element being a key, and the second its value. Each key is a string representing the name of an attribute, and each corresponding value is the value to add to the current transaction for this attribute. Values can be `int`, `float`, `string`, or `boolean`. Only the first 255 characters are retained for both keys and values.
+        Required. Each item in the list must be a `tuple`, with the first element being a _key_, and the second its _value_. Each key is a string representing the name of an attribute, and each corresponding value is the value to add to the current transaction for this attribute. Values can be `int`, `float`, `string`, or `boolean`. Only the first 255 characters are retained for both keys and values.
       </td>
     </tr>
   </tbody>
@@ -67,7 +67,7 @@ Returns `True` if all attributes were added successfully.
 
 An example of adding custom attributes to a [background task](/docs/agents/python-agent/python-agent-api/background_task):
 
-```
+```py
 @newrelic.agent.background_task()
 def send_request():
     response = requests.get("http://example.com")
@@ -80,7 +80,7 @@ def send_request():
 
 You can also use custom attributes to troubleshoot performance issues. For example, you might see occasional slow response times from a pool of memcache instances, but you don't know what instance is causing the problem. You might add an attribute to the transaction indicating the server, like so:
 
-```
+```py
 # Set server_ip to be the current server processing the transaction
 newrelic.agent.add_custom_attributes([
     ("memcache_query_frontend_lookup", "server_ip")