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##### value_at_key

###### Description

Returns the actual element type associated with a Key from the Sequence.

###### Synopsis

    template<
        typename Seq,
        typename Key>
    struct value_at_key
    {
        typedef unspecified type;
    };

Table 1.34. Parameters

Parameter | Requirement | Description
--- | --- | ---
`Seq` | A model of Associative Sequence | Argument sequence
`Key` | Any type | Key type

###### Expression Semantics

    result_of::value_at_key<Seq, Key>::type

Return type: Any type.

Precondition: `has_key<Seq, Key>::type::value == true` (where `Seq` is not Unbounded Sequence)

Semantics: Returns the actual element type associated with key type `Key` in `Seq`.

###### Header

    #include <boost/fusion/sequence/intrinsic/value_at_key.hpp>
    #include <boost/fusion/include/value_at_key.hpp>

###### Example

    typedef map<pair<int, char>, pair<char, char>, pair<double, char> > mymap;
    BOOST_MPL_ASSERT((boost::is_same<result_of::value_at_key<mymap, int>::type, char>));