title: Search for value in multi map
body: <p>Suppose I have the following:</p>
  
  <pre><code>class Foo {
  public:
      Foo(int x) {
          _x = x;
      }
      int _x;    
  }
  
  int main() {
      multimap&lt;string, Foo&gt; mm;
      Foo first_foo(5);
      Foo second_foo(10);
  
      mm.insert(pair&lt;string, Foo&gt;("A", first_foo));
      mm.insert(pair&lt;string, Foo&gt;("A", second_foo));
  
      Foo third_foo(10); 
  }
  </code></pre>
  
  <p>What's a nice way of checking if <code>third_foo</code> with key <code>"A"</code> is already in my <code>multimap</code>?</p>