message: elle.algorithm: contains for associative containers
diff: #pragma once
  #include <algorithm>
  +#include <map>
  +#include <unordered_map>
  +#include <boost/algorithm/cxx11/any_of.hpp>
  #include <boost/algorithm/cxx11/none_of.hpp>
  namespace elle
  {
  /// Whether \a e is in \a v.
  - ///
  - /// Get rid of it in favor of none_of_equal.
  template <typename Container, typename T>
  bool
  contains(Container const& c, T const& e)
  {
  - return ::boost::algorithm::none_of_equal(c, e);
  + return ::boost::algorithm::any_of_equal(c, e);
  + }
  +
  + /// Whether \a e is in \a v.
  + template <typename... Args, typename T>
  + bool
  + contains(std::unordered_map<Args...> const& c, T const& e)
  + {
  + return c.find(e) != c.end();
  + }
  +
  + /// Whether \a e is in \a v.
  + template <typename... Args, typename T>
  + bool
  + contains(std::map<Args...> const& c, T const& e)
  + {
  + return c.find(e) != c.end();
  }
  /// Emplace back only if not already in the vector.
  