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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 getSignatureKey(key, dateStamp, regionName, serviceName):
 """ Generate the signing key for AWS V4 requests. @param key: The secret key to use. @type key: L{bytes} @param dateStamp: The UTC date and time, serialized as an AWS date stamp. @type dateStamp: L{bytes} @param regionName: The name of the region. @type regionName: L{bytes} @param serviceName: The name of the service to which the request will be sent. @type serviceName: L{bytes} @return: The signature. @rtype: L{bytes} """

    kDate = sign((b'AWS4' + key), dateStamp)
    kRegion = sign(kDate, regionName)
    kService = sign(kRegion, serviceName)
    kSigning = sign(kService, b'aws4_request')
    return kSigning