How to use the djangoql.ast.Logical function in djangoql

def validate(self, node):
        """
        Validate DjangoQL AST tree vs. current schema
        """
        assert isinstance(node, Node)
        if isinstance(node.operator, Logical):
            self.validate(node.left)
            self.validate(node.right)
            return
        assert isinstance(node.left, Name)
        assert isinstance(node.operator, Comparison)
        assert isinstance(node.right, (Const, List))

        # Check that field and value types are compatible
        field = self.resolve_name(node.left)
        value = node.right.value
        if field is None:
            if value is not None:
                raise DjangoQLSchemaError(
                    'Related model %s can be compared to None only, but not to '
                    '%s' % (node.left.value, type(value).__name__)
                )

def build_filter(expr, schema_instance):
    if isinstance(expr.operator, Logical):
        left = build_filter(expr.left, schema_instance)
        right = build_filter(expr.right, schema_instance)
        if expr.operator.operator == 'or':
            return left | right
        else:
            return left & right

    field = schema_instance.resolve_name(expr.left)
    if not field:
        # That must be a reference to a model without specifying a field.
        # Let's construct an abstract lookup field for it
        field = DjangoQLField(
            name=expr.left.parts[-1],
            nullable=True,
        )
    return field.get_lookup(