in binding-cpp/gym_binding.cpp [233:241]
void observation_parse(const Json::Value& v, std::vector<float>& save_here)
{
if (!v.isArray())
throw std::runtime_error("cannot parse observation, not an array");
int s = v.size();
save_here.resize(s);
for (int i=0; i<s; ++i)
save_here[i] = v[i].asFloat();
}