def blob_already_exists(blob, dest_file):
    if isfile(dest_file):
        with open(dest_file, 'rb') as file:
            raw_crc = crc32(file.read())
        encoded = standard_b64encode(struct.pack('>I', raw_crc)).decode('ascii')
        return (encoded == blob.crc32c)
    return False
def blob_already_exists(blob, dest_file):
    if isfile(dest_file):
        with open(dest_file, 'rb') as file:
            raw_crc = crc32(file.read())
        encoded = standard_b64encode(struct.pack('>I', raw_crc)).decode('ascii')
        return (encoded == blob.crc32c)
    return False