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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def experiments_create(self, subject_id, image_group_id, properties):
 """Create an experiment object with subject, and image group. Objects are referenced by their unique identifiers. The API ensure that at time of creation all referenced objects exist. Referential consistency, however, is currently not enforced when objects are deleted. Expects experiment name in property list. Raises ValueError if no valid name is given. If any of the referenced objects do not exist a ValueError is thrown. Parameters subject_id : string Unique identifier of subject image_group_id : string Unique identifier of image group properties : Dictionary Set of experiment properties. Is required to contain at least the experiment name Returns ------- ExperimentHandle Handle for created experiment object in database """

        # Ensure that reference subject exists
        if self.subjects_get(subject_id) is None:
            raise ValueError('unknown subject: ' + subject_id)
        # Ensure that referenced image group exists
        if self.image_groups_get(image_group_id) is None:
            raise ValueError('unknown image group: ' + image_group_id)
        return self.experiments.create_object(subject_id, image_group_id, properties)