Accurate, consistent documentation

Keep all documentation (inline comments, docstrings, and changelog entries) accurate, concise, and consistent with established conventions. Specifically:

• Comments should explain why code exists or clarify non-obvious intent, not restate language semantics or mechanics the reader is expected to know (e.g., prefer # make error available outside except block (py3) over a long explanation of Python 3’s exception scoping).
• Docstrings must precisely describe behavior. Don’t use misleading terms (e.g., say “the current session object is reused” rather than “a copy is added” if no copy actually occurs).
• Follow the project’s established documentation style for consistency: use #: comments for documenting class/module-level attributes, and real docstrings (not trailing/dangling comments) for documenting methods, getters, and setters.
• Avoid duplicating details (such as default values or configuration) in multiple places like docstrings; instead, point to the single authoritative source (e.g., “see client.environ_base for defaults”) so documentation doesn’t drift out of sync with the code.
• Only add changelog/version-change notes for changes that affect public/user-facing behavior; skip changelog entries for internal-only or non-user-relevant changes.

Example of an accurate, properly placed docstring instead of a comment:

@property
def debug(self):
    """Whether debug mode is enabled. When using ``flask run`` ..."""
    return self.config["DEBUG"]

@debug.setter
def debug(self, value):
    self.config["DEBUG"] = value
    self.jinja_env.auto_reload = self.templates_auto_reload

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