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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 prep_folder(self, seq):
 """Take in a sequence string and prepares the folder for the I-TASSER run."""

        itasser_dir = op.join(self.root_dir, self.id)

        if not op.exists(itasser_dir):
            os.makedirs(itasser_dir)

        tmp = {self.id: seq}

        fasta.write_fasta_file_from_dict(indict=tmp,
                                         outname='seq',
                                         outext='.fasta',
                                         outdir=itasser_dir)
        return itasser_dir