Create this instance.

        See
        https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.instance.v1#google.spanner.admin.instance.v1.InstanceAdmin.CreateInstance

        .. note::

           Uses the ``project`` and ``instance_id`` on the current
           :class:`Instance` in addition to the ``display_name``.
           To change them before creating, reset the values via

           .. code:: python

              instance.display_name = 'New display name'
              instance.instance_id = 'i-changed-my-mind'

           before calling :meth:`create`.

        :rtype: :class:`google.api_core.operation.Operation`
        :returns: an operation instance
        :raises Conflict: if the instance already exists

def create(self):
        """Create this instance.

        See
        https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.instance.v1#google.spanner.admin.instance.v1.InstanceAdmin.CreateInstance

        .. note::

           Uses the ``project`` and ``instance_id`` on the current
           :class:`Instance` in addition to the ``display_name``.
           To change them before creating, reset the values via

           .. code:: python

              instance.display_name = 'New display name'
              instance.instance_id = 'i-changed-my-mind'

           before calling :meth:`create`.

        :rtype: :class:`google.api_core.operation.Operation`
        :returns: an operation instance
        :raises Conflict: if the instance already exists
        """
        api = self._client.instance_admin_api
        instance_pb = admin_v1_pb2.Instance(
            name=self.name,
            config=self.configuration_name,
            display_name=self.display_name,
            node_count=self.node_count,
        )
        metadata = _metadata_with_prefix(self.name)

        future = api.create_instance(
            parent=self._client.project_name,
            instance_id=self.instance_id,
            instance=instance_pb,
            metadata=metadata,
        )

        return future