add test code for return stmt.

issue: return statement which is child of for statement can't break loop and return the result.

  func test() {
    for i = 0; i < 10; i++ {
       if i == 5 {
          return i # can't return this value. also don't break this loop.
       }
    }
    return 0
  }
fix return stmt issue
Remove debug message
Merge branch 'pr/4'