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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 lsf(self, astr_path=""):
 """ List only the "files" in the astr_path. :param astr_path: path to list :return: "files" in astr_path, empty list if no files """

            d_files = self.ls(astr_path, nodes=False, data=True)
            l_files = d_files.keys()
            return l_files