=====Multiset Constructors=====
Syntax:

<code>
    #include <set>
    multiset();
    multiset( const multiset& c );
    multiset( input_iterator start, input_iterator end );
    multiset( input_iterator start, input_iterator end, const key_compare& cmp );
    explicit multiset( const key_compare& cmp );
    ~multiset();
</code>

Every multiset has a default constructor, copy constructor, and destructor.

The default constructor takes no arguments, creates a new instance of that
multiset, and runs in [[/complexity|constant time]]. The default copy constructor runs in
[[/complexity|linear time]] and can be used to create a new multiset that is a copy of the
given multiset c.

The default destructor is called when the multiset should be destroyed.