def METHOD_NAME(data: CoverageData, fullpath: bool = False) -> Dict[str, int]:
    """Return a dict summarizing the line coverage data.
    Keys are based on the file names, and values are the number of executed
    lines.  If `fullpath` is true, then the keys are the full pathnames of
    the files, otherwise they are the basenames of the files.
    Returns a dict mapping file names to counts of lines.
    """
    summ = {}
    filename_fn: Callable[[str], str]
    if fullpath:
        # pylint: disable=unnecessary-lambda-assignment
        filename_fn = lambda f: f
    else:
        filename_fn = os.path.basename
    for filename in data.measured_files():
        lines = data.lines(filename)
        assert lines is not None
        summ[filename_fn(filename)] = len(lines)
    return summ