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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 _BuildAuthenticatorResponse(self, app_id, client_data, plugin_response):
 """Builds the response to return to the caller."""

    encoded_client_data = self._Base64Encode(client_data)
    signature_data = str(plugin_response['signatureData'])
    key_handle = str(plugin_response['keyHandle'])

    response = {
        'clientData': encoded_client_data,
        'signatureData': signature_data,
        'applicationId': app_id,
        'keyHandle': key_handle,
    }
    return response