url.c_str(), (long long)num_bytes);
assert(pending_data.size() >= num_bytes);
pending_data.erase(pending_data.begin(), pending_data.begin() + num_bytes);
url.c_str(), (long long)num_bytes);
assert(pending_data.size() >= num_bytes);
pending_data.erase(pending_data.begin(), pending_data.begin() + num_bytes);