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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 validate(metadata):
 """Validator of the metadata composition :param metadata: conforming to the Metadata accepted by Ocean Protocol, dict :return: bool """

        # validate required sections and their sub items
        for section_key in Metadata.REQUIRED_SECTIONS:
            if section_key not in metadata or not metadata[section_key] or not isinstance(
                    metadata[section_key], dict):
                return False

            section = Metadata.MAIN_SECTIONS[section_key]
            section_metadata = metadata[section_key]
            for subkey in section.REQUIRED_VALUES_KEYS:
                if subkey not in section_metadata or section_metadata[subkey] is None:
                    return False

        return True