code: def p_identlist(self, t):
      '''identlist : IDENT
                    | NOT IDENT
                    | IDENT AND identlist
                    | NOT IDENT AND identlist              
                    '''
      if len(t)==5 : 
        #print(t[1],t[2],t[3],t[4])
        t[0] = t[1]+t[2]+t[3]+t[4]
      elif len(t)==4 : 
        #print(t[1],t[2],t[3])
        t[0] = t[1]+t[2]+t[3]
      elif len(t)==3 : 
        #print(t[1],t[2])
        t[0] = t[1]+t[2]
      elif len(t)==2 :
        #print(t[0],t[1])
        t[0]=t[1]
      else:
        print("Syntax error at '",str(t),"'"f p_identlist(self, t):
      '''identlist : IDENT
                    | NOT IDENT
                    | IDENT AND identlist
                    | NOT IDENT AND identlist              
                    '''
      if len(t)==5 : 
        #print(t[1],t[2],t[3],t[4])
        t[0] = t[1]+t[2]+t[3]+t[4]
      elif len(t)==4 : 
        #print(t[1],t[2],t[3])
        t[0] = t[1]+t[2]+t[3]
      elif len(t)==3 : 
        #print(t[1],t[2])
        t[0] = t[1]+t[2]
      elif len(t)==2 :
        #print(t[0],t[1])
        t[0]=t[1]
      else:
        print("Syntax error at '",str(t),"'")
docs: identlist : IDENT
                    | NOT IDENT
                    | IDENT AND identlist
                    | NOT IDENT AND identlist