======= AST Display =========================
Package
  ClassDeclList [1]
  . ClassDecl
  .   "A" classname
  .   FieldDeclList [0]
  .   MethodDeclList [1]
  .   . (public) MethodDecl
  .   .   ClassType
  .   .     "A" classname
  .   .   "p" methodname
  .   .   ParameterDeclList [0]
  .   .   StmtList [1]
  .   .   . WhileStmt
  .   .   .   LiteralExpr
  .   .   .     "true" BooleanLiteral
  .   .   .   BlockStmt
  .   .   .     StatementList [0]
=============================================