LimitedBuffer that pops element from front when inserting if maxSize is reached

LimitedBuffer.cpp

// queue::push/pop
#include <iostream>       // std::cin, std::cout
#include <deque>          // std::queue
#include <assert.h>

template<class T>
class LimitedBuffer
{
  
private:
  
  typedef std::deque<T> Buffer;
  
  Buffer _buffer;

  std::size_t _maxSize;
  
public:
  
  LimitedBuffer(std::size_t maxSize) : _maxSize(maxSize) { }
  
  typedef typename Buffer::iterator iterator;
  typedef typename Buffer::const_iterator const_iterator;

  iterator begin() { return _buffer.begin(); }

  iterator end()  { return _buffer.end(); }
  
  const_iterator begin() const { return _buffer.begin(); }

  const_iterator end()  const { return _buffer.end(); } 
  
  void push_back(T &fm)
  { 
    assert(_buffer.size() <= _maxSize);
    
    if(_buffer.size() == _maxSize) 
    {
      _buffer.pop_front();
    }
    _buffer.push_back(fm);
  }

};

template<class T>
void printLimitedBuffer(const LimitedBuffer<T>& lb)
{
    for(const T& elem : lb)
        std::cout << elem << "\t";
        
    std::cout << std::endl;
}

int main ()
{
  LimitedBuffer<int> myqueue(4);
  int myint;

  std::cout << "Please enter some integers (enter 0 to end):\n";

  do {
    std::cin >> myint;
    myqueue.push_back(myint);
    
    std::cout << "Contains: " ;
    printLimitedBuffer(myqueue);
    
  } while (myint);


  return 0;
}