code: def parameters(self):
          
          nodes = []
          self._process(Nature.LPAREN)
  
          while self.token.nature != Nature.RPAREN:
  
              nodes.append(Parameters(variable=self.logical_or_expr()))
  
              if self.token.nature == Nature.COMMA:
                  self._process(Nature.COMMA)
  
          self._process(Nature.RPAREN)
          return nodes
docs: parameters: '(' logical_or_expr (',' logical_or_expr)* ')'