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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 _der_to_raw(self, der_signature):
 """Convert signature from DER encoding to RAW encoding."""

        r, s = decode_dss_signature(der_signature)
        component_length = self._sig_component_length()
        return int_to_bytes(r, component_length) + int_to_bytes(s, component_length)