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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 verify(self, verify_locations: str) -> None: """Verify that the OCSP response is trusted. Args: verify_locations: The file path to a trust store containing pem-formatted certificates, to be used for validating the OCSP response. Raises OcspResponseNotTrustedError if the validation failed ie. the OCSP response is not trusted. """

        # Ensure the file exists
        with open(verify_locations):
            pass

        try:
            self._ocsp_response.basic_verify(verify_locations)
        except _nassl.OpenSSLError as e:
            if 'certificate verify error' in str(e):
                raise OcspResponseNotTrustedError(verify_locations)
            raise