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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 list_commands(self, ctx):
 """List commands from folder."""

        rv = []
        files = [_ for _ in next(os.walk(self.folder))[2] if not _.startswith("_") and _.endswith(".py")]
        for filename in files:
            rv.append(filename[:-3])
        rv.sort()
        return rv