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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 mime_type(self, type_: Optional[MimeType] = None) -> str: """Get a random mime type from list. :param type_: Enum object MimeType. :return: Mime type. """

        key = self._validate_enum(item=type_, enum=MimeType)
        types = MIME_TYPES[key]
        return self.random.choice(types)