Test, validate and match regular expressions
Matches lines that name a Python executable such as 'python', 'python3', 'python3.8', or 'python3.8m'. It allows an optional major version '3', an optional minor version (a dot followed by a single digit), and an optional 'm' suffix used for Python's ABI/memory-optimized builds. With multiline anchoring, each line must be exactly one of these names, making it useful for validating shebang lines, process lists, or interpreter names.