code: func (db *MemDB) Snapshot() *MemDB {
  	clone := &MemDB{
  		schema:  db.schema,
  		root:    unsafe.Pointer(db.getRoot()),
  		primary: false,
  	}
  	return clone
  }
docs: // Snapshot is used to capture a point-in-time snapshot
  // of the database that will not be affected by any write
  // operations to the existing DB.