code: def fromstring(cls, rs3_string):
          
          temp = tempfile.NamedTemporaryFile(delete=False)
          temp.write(rs3_string)
          temp.close()
          rst_tree = cls(rs3_file=temp.name)
          os.unlink(temp.name)
          return rst_tree
docs: Create an RSTTree instance from a string content an *.rs3 file.