When inputs or response fields are optional/nullable, preserve their semantics explicitly and avoid unsafe coercion or indexing. Apply these rules: 1) Don’t coerce `None` with `bool(...)` when `None` has distinct meaning. If you mean “unset,” omit the field/parameter rather than converting it. 2) Don’t blindly index into dicts/JSON (`obj["key"]`) when keys may be missing; use `obj.get("key", default)` (often `{}`) to prevent exceptions. 3) When building request artifacts (e.g., headers), only include values when the input is actually present; otherwise, send an empty structure or omit the header. Example patterns: ```python # 1) Tri-state optional: None => omit payload = {} if by_alias is not None: payload["by_alias"] = by_alias # preserve None-vs-explicit # 2) Safe dict access error_data = response.data.get("error", {}) message = error_data.get("message", "Operation failed") # 3) Conditional auth header headers = {} if not api_key else {"Authorization": f"Bearer {api_key}"} ``` Result: fewer runtime KeyErrors/invalid requests, and correct behavior when upstream defaults/configuration rely on “unset” vs “explicit value.”