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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 _copy_update(sourcepath, destname):
 """Copy source to dest only if source is newer."""

    if sys.platform.startswith('linux'):
        return os.system("/bin/cp -ua '%s' '%s'" % (sourcepath, destname))
    else:
        return os.system("rsync -ua '%s' '%s'" % (sourcepath, destname))