Handle missing keys in a dictionary

Write get_nested(data, path, default=None) which attempts to retrieve a nested value from data using path. Requirements: - data may be a dictionary or nested combinations of dicts and lists. - path can be either a list/tuple of keys/indices or a dot-separated string (e.g., 'a.b.0.c'). - When following the path: - If the current value is a dict and the next token is a key present in it, continue. - If the current value is a list (or tuple) and the next token is an integer index (string or int), access that index when valid. - If any step is invalid (missing key, index out of range, wrong type), return default without raising an exception. - Return the final value if found. Design for defensive behavior and simple usage in data processing pipelines.

Implement a helper that retrieves a nested value by path, tolerating absent keys or wrong types and returning a default.

Do not raise exceptions for missing keys or wrong types. Support integer index tokens for list access.