Fetches the version number from the package's __init__.py file

def _get_version():
    """
    Fetches the version number from the package's __init__.py file
    """
    with open('Lib/fontParts/__init__.py', 'r', encoding='utf-8') as f:
        for line in f:
            if line.startswith(u'__version__'):
                return ast.parse(line).body[0].value.s
        raise RuntimeError("No __version__ string found!")