(Program
  (ExpressionStatements
    (Class
      (Identifier)
    {+(FieldDecl
        (Identifier)
        (NumberLiteral))+}
      (Method
      { (Identifier)
      ->(Identifier) }
        (Params
          (Other "required_parameter"
            (Identifier)))
        (Return
          (Identifier)))
      (Method
      { (Identifier)
      ->(Identifier) }
        (Params
          (Other "required_parameter"
            (Identifier)))
        (Return
          (Identifier)))
      (Method
      { (Identifier)
      ->(Identifier) }
        (Params
          (Other "required_parameter"
            (Identifier)))
        (Return
          (Identifier))))))