======= AST Display =========================
Package
  ClassDeclList [2]
  . ClassDecl
  .   "MainClass" classname
  .   FieldDeclList [0]
  .   MethodDeclList [1]
  .   . (public static) MethodDecl
  .   .   VOID BaseType
  .   .   "main" methodname
  .   .   ParameterDeclList [1]
  .   .   . ParameterDecl
  .   .   .   ArrayType
  .   .   .     ClassType
  .   .   .       "String" classname
  .   .   .   "args"parametername 
  .   .   StmtList [0]
  . ClassDecl
  .   "SuperClass" classname
  .   FieldDeclList [0]
  .   MethodDeclList [4]
  .   . (public) MethodDecl
  .   .   VOID BaseType
  .   .   "setWorth" methodname
  .   .   ParameterDeclList [1]
  .   .   . ParameterDecl
  .   .   .   INT BaseType
  .   .   .   "worth"parametername 
  .   .   StmtList [1]
  .   .   . AssignStmt
  .   .   .   IdRef
  .   .   .     "integer" Identifier
  .   .   .   RefExpr
  .   .   .     IdRef
  .   .   .       "worth" Identifier
  .   . (public) MethodDecl
  .   .   INT BaseType
  .   .   "getWorth" methodname
  .   .   ParameterDeclList [0]
  .   .   StmtList [0]
  .   .   RefExpr
  .   .     QualifiedRef
  .   .       "integer" Identifier
  .   .       ThisRef
  .   . (public) MethodDecl
  .   .   VOID BaseType
  .   .   "setTruth" methodname
  .   .   ParameterDeclList [1]
  .   .   . ParameterDecl
  .   .   .   BOOLEAN BaseType
  .   .   .   "truth"parametername 
  .   .   StmtList [1]
  .   .   . AssignStmt
  .   .   .   IdRef
  .   .   .     "bool" Identifier
  .   .   .   RefExpr
  .   .   .     IdRef
  .   .   .       "truth" Identifier
  .   . (public) MethodDecl
  .   .   INT BaseType
  .   .   "getTruth" methodname
  .   .   ParameterDeclList [0]
  .   .   StmtList [0]
  .   .   RefExpr
  .   .     QualifiedRef
  .   .       "bool" Identifier
  .   .       ThisRef
=============================================