docs: def p_term_var(self, p):
          ''' term   :    VAR 
          '''
          _LOGGER.debug("term -> VAR")
          
          # TODO: determine the type of the var
          if p[1] not in self._VAR_VALUES:
              if self._autodefine_vars:
                  self._VAR_VALUES[p[1]] = TypedClass(None, TypedClass.UNKNOWN)
                  
          if p[1] in self._VAR_VALUES:
              _LOGGER.debug("term -> VAR")
              p[0] = self._VAR_VALUES[p[1]]
          else:
              raise UndefinedVar()