def verify_signature(self, signature_filename, data_filename,
                         keystore=None):
        """
        Verify a signature for a file.

        :param signature_filename: The pathname to the file containing the
                                   signature.
        :param data_filename: The pathname to the file containing the
                              signed data.
        :param keystore: The path to a directory which contains the keys
                         used in verification. If not specified, the
                         instance's ``gpg_home`` attribute is used instead.
        :return: True if the signature was verified, else False.
        """
        if not self.gpg:
            raise DistlibException('verification unavailable because gpg '
                                   'unavailable')
        cmd = self.get_verify_command(signature_filename, data_filename,
                                      keystore)
        rc, stdout, stderr = self.run_command(cmd)
        if rc not in (0, 1):
            raise DistlibException('verify command failed with error '
                             'code %s' % rc)
        return rc == 0

        Verify a signature for a file.

        :param signature_filename: The pathname to the file containing the
                                   signature.
        :param data_filename: The pathname to the file containing the
                              signed data.
        :param keystore: The path to a directory which contains the keys
                         used in verification. If not specified, the
                         instance's ``gpg_home`` attribute is used instead.
        :return: True if the signature was verified, else False.
        
product/gradle-plugin/src/main/python/pip/_vendor/distlib/index.py