Determine whether a file or folder actually exists.

def check_existence(to_check, name, config_key=None, relative_to=None,
                    allow_undefined=False, allow_not_existing=False,
                    base_key='releaser'):
    """Determine whether a file or folder actually exists."""
    if allow_undefined and (to_check is None or to_check.lower() == 'none'):
        print("{: <14} -> {}UNDEFINED{}".format(name, WARNING_COLOR,
                                                RESET_COLOR))
        return
    else:
        if config_key is None:
            config_key = "{}.{}".format(base_key, name)
        my_check = Path(to_check).resolve()
        if my_check.exists() and relative_to is not None:
            printed_path = str(my_check.relative_to(relative_to))
            if printed_path != '.':
                printed_path = '.' + os.sep + printed_path
        else:
            printed_path = str(my_check)
        if my_check.exists() or allow_not_existing:
            print("{: <14} -> {}".format(name, printed_path))
            return
        else:
            raise FileNotFoundError("[{}ERROR{}] '{}', as given, doesn't "
                                    "exist. For configuration key '{}', was "
                                    "given: {}".format(ERROR_COLOR, RESET_COLOR,
                                                       name, config_key,
                                                       to_check))