C++: Error outputting a custom hash key value from unordered_map to std::cout

I am trying to build an std::unordered_map with a custom type as a key. The custom type is a simple std::vector<double>. The idea is that it will function as a convenient container for 2D points on a grid. Everything is working correctly except for outputting the hashed key. Here is a sample I put together to illustrate the idea:

#include <iostream>
#include <vector>
#include <unordered_map>
#include <boost/functional/hash.hpp>
#include <chrono>

namespace std{
        template<typename Container>
        struct hash {
                        std::size_t operator()(Container const& v) const
                        {
                                return boost::hash_range(v.begin(), v.end());
                        }
        };
}

int main()
{

        std::unordered_map<std::vector<double>, double> test;

        unsigned long t = (unsigned long) std::chrono::system_clock::now().time_since_epoch().count();
        std::srand(t);
        for (uint i = 0; i < 100 ; ++i)
        {
                double d1 = i/200.0;
                double d2 = i/200.0;
                std::vector<double> v({d1, d2});
                test[v] = d1;
        }

        std::cout << "Size:" << test.size() << std::endl;
        for (const auto& it : test )
        {
                std::cout << it.first << ":" << it.second << std::endl;
        }

        return 0;
}

The hash specialisation template is courtesy of another SE thread. The trouble is that g++ spits out the following error when I try to compile the above:

cannot bind 'std::ostream {aka std::basic_ostream<char>}' lvalue to 'std::basic_ostream<char>&&'
   std::cout << it.first << ":" << it.second << std::endl;
                   ^

It is obvious that it stumbles on it.first. The code compiles and runs correctly if I remove it.first. I understand that the output will not be a vector of doubles. I did look around SE for quite a while, but I couldn't find a definitive answer on how to std::cout the hash value from an unordered map with a custom key type. Any feedback will be highly appreciated.

Thank you in advance!