(Program
  (ExpressionStatements
    (Function
      (Params
        (Other "required_parameter"
        { (Identifier)
        ->(Identifier) })
        (Other "required_parameter"
          (Identifier)))
      (Return
        (MathOperator
        { (Identifier)
        ->(Identifier) }
        { (Other "*")
        ->(Other "+") }
        { (Identifier)
        ->(Identifier) })))))