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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 findall(self):
 """Find all files under the base and set ``allfiles`` to the absolute pathnames of files found. """

        from stat import S_ISREG, S_ISDIR, S_ISLNK

        self.allfiles = allfiles = []
        root = self.base
        stack = [root]
        pop = stack.pop
        push = stack.append

        while stack:
            root = pop()
            names = os.listdir(root)

            for name in names:
                fullname = os.path.join(root, name)

                # Avoid excess stat calls -- just one will do, thank you!
                stat = os.stat(fullname)
                mode = stat.st_mode
                if S_ISREG(mode):
                    allfiles.append(fsdecode(fullname))
                elif S_ISDIR(mode) and not S_ISLNK(mode):
                    push(fullname)