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            Returns the result type of has_key.
          
template< typename Seq, typename Key> struct has_key { typedef unspecified type; };
Table 1.32. Parameters
| Parameter | Requirement | Description | 
|---|---|---|
| 
                       | A model of Associative Sequence | Argument sequence | 
| 
                       | Any type | Key type | 
result_of::has_key<Seq, Key>::type
Return type: An MPL Integral Constant.
            Semantics: Returns mpl::true_
            if Seq contains an element
            with key type Key, returns
            mpl::false_ otherwise.
          
#include <boost/fusion/sequence/intrinsic/has_key.hpp> #include <boost/fusion/include/has_key.hpp>
typedefmap<pair<int, char>,pair<char, char>,pair<double, char> > mymap; BOOST_MPL_ASSERT((result_of::has_key<mymap, int>)); BOOST_MPL_ASSERT_NOT((result_of::has_key<mymap, void*>));