import glob


def find_paths(initial_path, extension):
    """
    From a path, return all the  files of a given extension inside.
    :param initial_path: the initial directory of search
    :param extension: the extension of the files to be searched
    :return: list of paths inside the initial path
    """

    paths = glob.glob(initial_path+r'/**/*.' + extension, recursive=True)

    return paths