text: // Basic examples for $bit
  var res;
  var coll = db.update_bit;
  coll.drop();
  
  // $bit and
  coll.remove({});
  coll.save({_id:1, a:NumberInt(2)});
  res = coll.update({}, {$bit: {a: {and: NumberInt(4)}}});
  assert.writeOK(res);
  assert.eq(coll.findOne().a, 0);
  
  // $bit or
  coll.remove({});
  coll.save({_id:1, a:NumberInt(2)});
  res = coll.update({}, {$bit: {a: {or: NumberInt(4)}}});
  assert.writeOK(res);
  assert.eq(coll.findOne().a, 6);
  
  // $bit xor
  coll.remove({});
  coll.save({_id:1, a:NumberInt(0)});
  res = coll.update({}, {$bit: {a: {xor: NumberInt(4)}}});
  assert.writeOK(res);
  assert.eq(coll.findOne().a, 4);
  
  // SERVER-19706 Empty bit operation.
  res = coll.update({}, {$bit: {a: {}}});
  assert.writeError(res);
  