When working with nullable/optional values, treat None (absence) differently from other falsy values like "" (empty string) or 0 (zero). Use explicit is not None checks when empty values are valid, and avoid repeating null checks after you’ve already established a non-null invariant via an early return/guard.

Apply it like this:

• Prefer if x is not None: over if x: when x may be an empty string/zero but should still be considered “present”.
• After an early return for None, don’t add redundant x is not None guards later.

Example:

import os

bearer = os.getenv("AWS_BEARER_TOKEN_BEDROCK")
# Empty string is a valid value, so check for None (absence), not truthiness.
if bearer is not None:
    headers["Authorization"] = f"Bearer {bearer}"

# Later, avoid redundant None checks after a guard/early return:
if response is None:
    return
if response.get("content"):
    append_messages(message, response)