(Program
  (ExpressionStatements
    (Class
      (Identifier)
      (FieldDecl
        (Identifier)
        (NumberLiteral))
      (Method
        (Identifier)
        (Params
          (Other "required_parameter"
            (Identifier)))
        (Return
          (Identifier)))
      (Method
        (Identifier)
        (Params
          (Other "required_parameter"
            (Identifier)))
        (Return
          (Identifier)))
      (Method
        (Identifier)
        (Params
          (Other "required_parameter"
            (Identifier)))
        (Return
          (Identifier))))))