Finds a given cyther resource in the 'test' subdirectory in
    'cyther' package

def find_resource(r, *, pkg='cyther'):
    """
    Finds a given cyther resource in the 'test' subdirectory in
    'cyther' package
    """
    file_path = pkg_resources.resource_filename(pkg, os.path.join('test', r))
    if not os.path.isfile(file_path):
        msg = "Resource '{}' does not exist"
        raise FileNotFoundError(msg.format(file_path))
    return file_path