program test()

  var b := { { 0, 0 } };
  print( b );

  b.insert( 1, { 21, 31 } );
  print( b );
  b.erase( 11 );

  b.insert( 1, { 22, 32 } );
  print( b );
  b.erase( 11 );

  b.insert( 1, { 23, 33 } );
  print( b );
  b.erase( 11 );

endprogram

/**** Expected Output Begins: *****
(no)
*****  Expected Output Ends   ****/