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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 accept(self):
 # type: () -> str """The content-type for the response to the client. Returns: (str):
 The value of the header 'Accept' or the user-supplied SAGEMAKER_DEFAULT_INVOCATIONS_ACCEPT environment variable. """

        accept = self.headers.get('Accept')

        if not accept or accept == _content_types.ANY:
            return self._default_accept
        else:
            return accept