<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def goto(self, iroute: "InstanceRoute") -> "InstanceNode": """Move the focus to an instance inside the receiver's value. Args: iroute: Instance route (relative to the receiver). Returns: The instance node corresponding to the target instance. Raises: InstanceValueError: If `iroute` is incompatible with the receiver's value. NonexistentInstance: If the instance node doesn't exist. NonDataNode: If an instance route addresses a non-data node (rpc/action/notification). """

        inst = self
        for sel in iroute:
            inst = sel.goto_step(inst)
        return inst