======= AST Display =========================
Package
  ClassDeclList [1]
  . ClassDecl
  .   "LegalStmt" classname
  .   FieldDeclList [0]
  .   MethodDeclList [1]
  .   . (public) MethodDecl
  .   .   VOID BaseType
  .   .   "main" methodname
  .   .   ParameterDeclList [0]
  .   .   StmtList [1]
  .   .   . CallStmt
  .   .   .   ThisRef
  .   .   .   ExprList [2]
  .   .   .   . LiteralExpr
  .   .   .   .   "3" IntLiteral
  .   .   .   . LiteralExpr
  .   .   .   .   "4" IntLiteral
=============================================