======= AST Display =========================
Package
  ClassDeclList [1]
  . ClassDecl
  .   "A" classname
  .   FieldDeclList [0]
  .   MethodDeclList [1]
  .   . (public) MethodDecl
  .   .   ClassType
  .   .     "A" classname
  .   .   "p" methodname
  .   .   ParameterDeclList [0]
  .   .   StmtList [0]
  .   .   RefExpr
  .   .     ThisRef
=============================================