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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 _sha256_sign(self, method, url, headers, body):
 """Sign the request with SHA256. """

        d = ''
        sign_headers = method.upper() + '|' + url + '|'
        for key, value in sorted(headers.items()):
            if key.startswith('X-Mcash-'):
                sign_headers += d + key.upper() + '=' + value
                d = '&'

        rsa_signature = base64.b64encode(
            self.signer.sign(SHA256.new(sign_headers)))

        return 'RSA-SHA256 ' + rsa_signature