code: def _exist(self, name):
          
          cmd = 'exist("%s")' % name
          resp = self._engine.eval(cmd, silent=True).strip()
          exist = int(resp.split()[-1])
          if exist == 0:
              msg = 'Value "%s" does not exist in Octave workspace'
              raise Oct2PyError(msg % name)
          return exist
docs: Test whether a name exists and return the name code.
  
          Raises an error when the name does not exist.