How to use the eventsourcing.domain.model.events.DomainEvent function in eventsourcing

# Check the repo now raises a KeyError.
        self.assertRaises(KeyError, repo.__getitem__, entity1.id)

        # Check the entity can't be discarded twice.
        self.assertRaises(AssertionError, entity1.discard)

        # Should fail to validate event with wrong entity ID.
        self.assertRaises(EntityIDConsistencyError,
                          entity2._validate_originator,
                          DomainEvent(entity_id=entity2.id+'wrong', entity_version=0)
                          )
        # Should fail to validate event with wrong entity version.
        self.assertRaises(EntityVersionConsistencyError,
                          entity2._validate_originator,
                          DomainEvent(entity_id=entity2.id, entity_version=0)
                          )
        # Should validate event with correct entity ID and version.
        entity2._validate_originator(
            DomainEvent(entity_id=entity2.id, entity_version=entity2.version)
        )

        # Check an entity can be reregistered with the same ID.
        replacement_event = Example.Created(entity_id=entity1.id, a=11, b=12)
        # replacement = Example.mutate(event=replacement_event)
        publish(event=replacement_event)

        # Check the replacement entity can be retrieved from the example repository.
        replacement = repo[entity1.id]
        assert isinstance(replacement, Example)
        self.assertEqual(replacement.a, 11)
        self.assertEqual(replacement.b, 12)

self.assertEqual(3, entity1.count_heartbeats())
        self.assertEqual(3, repo[entity1.id].count_heartbeats())

        # Check the entity can be discarded.
        entity1.discard()

        # Check the repo now raises a KeyError.
        self.assertRaises(KeyError, repo.__getitem__, entity1.id)

        # Check the entity can't be discarded twice.
        self.assertRaises(AssertionError, entity1.discard)

        # Should fail to validate event with wrong entity ID.
        self.assertRaises(EntityIDConsistencyError,
                          entity2._validate_originator,
                          DomainEvent(entity_id=entity2.id+'wrong', entity_version=0)
                          )
        # Should fail to validate event with wrong entity version.
        self.assertRaises(EntityVersionConsistencyError,
                          entity2._validate_originator,
                          DomainEvent(entity_id=entity2.id, entity_version=0)
                          )
        # Should validate event with correct entity ID and version.
        entity2._validate_originator(
            DomainEvent(entity_id=entity2.id, entity_version=entity2.version)
        )

        # Check an entity can be reregistered with the same ID.
        replacement_event = Example.Created(entity_id=entity1.id, a=11, b=12)
        # replacement = Example.mutate(event=replacement_event)
        publish(event=replacement_event)

# Check the entity can't be discarded twice.
        self.assertRaises(AssertionError, entity1.discard)

        # Should fail to validate event with wrong entity ID.
        self.assertRaises(EntityIDConsistencyError,
                          entity2._validate_originator,
                          DomainEvent(entity_id=entity2.id+'wrong', entity_version=0)
                          )
        # Should fail to validate event with wrong entity version.
        self.assertRaises(EntityVersionConsistencyError,
                          entity2._validate_originator,
                          DomainEvent(entity_id=entity2.id, entity_version=0)
                          )
        # Should validate event with correct entity ID and version.
        entity2._validate_originator(
            DomainEvent(entity_id=entity2.id, entity_version=entity2.version)
        )

        # Check an entity can be reregistered with the same ID.
        replacement_event = Example.Created(entity_id=entity1.id, a=11, b=12)
        # replacement = Example.mutate(event=replacement_event)
        publish(event=replacement_event)

        # Check the replacement entity can be retrieved from the example repository.
        replacement = repo[entity1.id]
        assert isinstance(replacement, Example)
        self.assertEqual(replacement.a, 11)
        self.assertEqual(replacement.b, 12)

def test_not_implemented_error(self):
        # Define an event class.
        class UnsupportedEvent(DomainEvent): pass

        # Check we get an error when attempting to mutate on the event.
        self.assertRaises(NotImplementedError, Example.mutate, Example, UnsupportedEvent('1', '0'))

self._canonize_suffix(suffix, string)


class SuffixTreeNode(EventSourcedEntity):
    """A node in the suffix tree.
    """

    class Created(EventSourcedEntity.Created): pass

    class AttributeChanged(EventSourcedEntity.AttributeChanged): pass

    class Discarded(EventSourcedEntity.Discarded): pass

    class ChildNodeAdded(DomainEvent): pass

    class ChildNodeRemoved(DomainEvent): pass

    def __init__(self, suffix_node_id=None, string_id=None, *args, **kwargs):
        super(SuffixTreeNode, self).__init__(*args, **kwargs)
        self._suffix_node_id = suffix_node_id
        self._string_id = string_id
        self._child_node_ids = OrderedDict()

    @mutableproperty
    def suffix_node_id(self):
        """The id of a node with a matching suffix, representing a suffix link.

        None indicates this node has no suffix link.
        """

    @mutableproperty
    def string_id(self):

from eventsourcing.exceptions import (
    EntityIsDiscarded,
    HeadHashError,
    OriginatorIDError,
    OriginatorVersionError,
)
from eventsourcing.utils.times import decimaltimestamp_from_uuid
from eventsourcing.utils.topic import get_topic, resolve_topic


class DomainEntity(object):
    """
    Supertype for domain model entity.
    """

    class Event(EventWithOriginatorID, DomainEvent):
        """
        Supertype for events of domain model entities.
        """

        # def __mutate__(self, obj):
        #     # Call super method.
        #     return super(DomainEntity.Event, self).__mutate__(obj)

        def __check_obj__(self, obj: "DomainEntity"):
            """
            Checks state of obj before mutating.

            :param obj: Domain entity to be checked.

            :raises OriginatorIDError: if the originator_id is mismatched
            """

def __eq__(self, other: object) -> bool:
        """
        Tests for equality of two event objects.

        :rtype: bool
        """
        return isinstance(other, DomainEvent) and self.__hash__() == other.__hash__()

suffix.first_char_index += e.length + 1
                suffix.source_node_id = e.dest_node_id
                self._canonize_suffix(suffix, string)


class SuffixTreeNode(EventSourcedEntity):
    """A node in the suffix tree.
    """

    class Created(EventSourcedEntity.Created): pass

    class AttributeChanged(EventSourcedEntity.AttributeChanged): pass

    class Discarded(EventSourcedEntity.Discarded): pass

    class ChildNodeAdded(DomainEvent): pass

    class ChildNodeRemoved(DomainEvent): pass

    def __init__(self, suffix_node_id=None, string_id=None, *args, **kwargs):
        super(SuffixTreeNode, self).__init__(*args, **kwargs)
        self._suffix_node_id = suffix_node_id
        self._string_id = string_id
        self._child_node_ids = OrderedDict()

    @mutableproperty
    def suffix_node_id(self):
        """The id of a node with a matching suffix, representing a suffix link.

        None indicates this node has no suffix link.
        """

# Make sure events that are applied to the entity have originated
    # from the entity at the version the instance it is current at.
    #  - this assumes _validate_originator() is called in mutators.
    __always_validate_originator_version__ = True

    class Created(EventSourcedEntity.Created):
        pass

    class AttributeChanged(EventSourcedEntity.AttributeChanged):
        pass

    class Discarded(EventSourcedEntity.Discarded):
        pass

    class Heartbeat(DomainEvent):
        pass

    def __init__(self, a, b, **kwargs):
        super(Example, self).__init__(**kwargs)
        self._a = a
        self._b = b
        self._count_heartbeats = 0

    @mutableproperty
    def a(self):
        return self._a

    @mutableproperty
    def b(self):
        return self._b