method type hint currently errors

[Roger-luo]

[kaihsin]

@basic
def main() -> ir.Method[[int], float]:
    def test(x: int) -> float:
        return x * 3.0 
    
    return test 

Currently gets:

BuildError: expect a type hint, got ir.Method[[int], float]
Source Traceback:
  File "/Users/khwu/kirin-workspace/test_hint.py", line 9, col 0
   │  @basic
  9│  def main() -> ir.Method[, float]:
   │  ^^^^^^^^^^^^^^^
   │      def test(x: int) -> float:
   │          return x * 3.0 
   │  
   │      return test 

[kaihsin]

completed and enhanced via #395 and #582