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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 get_pdffilepath(pdffilename):
 """ Returns the path for the pdf file args: pdffilename: string returns path for the plots folder / pdffilename.pdf """

        return FILEPATHSTR.format(
            root_dir=ROOT_DIR, os_sep=os.sep, os_extsep=os.extsep,
            name=pdffilename,
            folder=PURPOSE.get("plots").get("folder", "plots"),
            ext=PURPOSE.get("plots").get("extension", "pdf")
        )