code: def exists(self):
          
          api = self._client.instance_admin_api
          metadata = _metadata_with_prefix(self.name)
  
          try:
              api.get_instance(self.name, metadata=metadata)
          except NotFound:
              return False
  
          return True
docs: Test whether this instance exists.
  
          See
          https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.instance.v1#google.spanner.admin.instance.v1.InstanceAdmin.GetInstanceConfig
  
          :rtype: bool
          :returns: True if the instance exists, else false