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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 signature(cert, sig, body):
 """Validate data request signature. See `validate.request` for additional info. Args: cert: cryptography.hazmat.backends.openssl.x509._Certificate. The Amazon signing certificate. sig: str. Signature header value sent by request. body: str. HTTPS request body. Returns: bool: True if valid, False otherwise. """

    body = six.b(body)

    sig = base64.decodestring(sig)
    padder = padding.PKCS1v15()
    public_key = cert.public_key()
    try:
        public_key.verify(sig, body, padder, hashes.SHA1())
        return True
    except InvalidSignature:
        warnings.warn('Signature verification failed.')
        return False