def download(self):
    import tarfile
    if self._check_integrity():
        print('Files already downloaded and verified')
        return
    root = self.root
    download_url(self.url, root, self.filename, self.tgz_md5)
    cwd = os.getcwd()
    tar = tarfile.open(os.path.join(root, self.filename), 'r:gz')
    os.chdir(root)
    tar.extractall()
    tar.close()
    os.chdir(cwd)
def download(self):
    import tarfile
    if self._check_integrity():
        print('Files already downloaded and verified')
        return
    root = self.root
    download_url(self.url, root, self.filename, self.tgz_md5)
    cwd = os.getcwd()
    tar = tarfile.open(os.path.join(root, self.filename), 'r:gz')
    os.chdir(root)
    tar.extractall()
    tar.close()
    os.chdir(cwd)