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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 assistant_from_yaml(cls, source, y, superassistant, fully_loaded=True, role=settings.DEFAULT_ASSISTANT_ROLE):
 """Constructs instance of YamlAssistant loaded from given structure y, loaded from source file source. Args: source: path to assistant source file y: loaded yaml structure superassistant: superassistant of this assistant Returns: YamlAssistant instance constructed from y with source file source Raises: YamlError: if the assistant is malformed """

        # In pre-0.9.0, we required assistant to be a mapping of {name: assistant_attributes}
        # now we allow that, but we also allow omitting the assistant name and putting
        # the attributes to top_level, too.
        name = os.path.splitext(os.path.basename(source))[0]
        yaml_checker.check(source, y)
        assistant = yaml_assistant.YamlAssistant(name, y, source, superassistant,
            fully_loaded=fully_loaded, role=role)

        return assistant