code: func (c *Conn) Backup(dst *Conn) error {
  	return copyDatabase(dst.sqlite, c.sqlite)
  }
docs: // Backup writes a snapshot of the database over the given database
  // connection, erasing all the contents of the destination database.
  // The consistency of the snapshot is READ_COMMITTED relative to any
  // other connections currently open to this database. The caller must
  // ensure that all connections to the destination database are not
  // accessed during this operation.