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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:
 async def json(self, *, encoding: str=None, loads: JSONDecoder=DEFAULT_JSON_DECODER, content_type: Optional[str]='application/json') -> Any: """Read and decodes JSON response."""

        if self._body is None:
            await self.read()

        if content_type:
            ctype = self.headers.get(hdrs.CONTENT_TYPE, '').lower()
            if not _is_expected_content_type(ctype, content_type):
                raise ContentTypeError(
                    self.request_info,
                    self.history,
                    message=('Attempt to decode JSON with '
                             'unexpected mimetype: %s' % ctype),
                    headers=self.headers)

        if encoding is None:
            encoding = self.get_encoding()

        return loads(self._body.decode(encoding))