======= AST Display =========================
Package
  ClassDeclList [1]
  . ClassDecl
  .   "Foo" classname
  .   FieldDeclList [0]
  .   MethodDeclList [1]
  .   . (public) MethodDecl
  .   .   VOID BaseType
  .   .   "bar" methodname
  .   .   ParameterDeclList [0]
  .   .   StmtList [1]
  .   .   . VarDeclStmt
  .   .   .   VarDecl
  .   .   .     ArrayType
  .   .   .       INT BaseType
  .   .   .     "newarr" varname
  .   .   .   NewArrayExpr
  .   .   .     INT BaseType
  .   .   .     LiteralExpr
  .   .   .       "20" IntLiteral
=============================================