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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 _from_directory(self, dirname, prefix=""):
 """Add dataset from files in a directory. Parameters dirname : string Directory name. prefix : string Prefix. """

        ps = [os.path.join(here, dirname, p) for p in os.listdir(os.path.join(here, dirname))]
        n = prefix + wt_kit.string2identifier(os.path.basename(dirname))
        setattr(self, n, ps)