fix linter errors #127

	name: build-and-test-rpn
	on: [push, pull_request]
	jobs:
	build:
	strategy:
	matrix:
	version: [1.21]
	os: [ubuntu-latest, windows-latest, macos-latest]
	name: Build
	runs-on: ${{ matrix.os }}
	steps:
	- name: Set up Go
	uses: actions/setup-go@v3
	with:
	go-version: ${{ matrix.version }}
	id: go

	- name: checkout
	uses: actions/checkout@v3

	- name: build
	run: go build

	- name: test
	run: make test

	golangci:
	name: lint
	runs-on: ubuntu-latest
	steps:
	- uses: actions/setup-go@v3
	with:
	go-version: 1.21
	- uses: actions/checkout@v3
	- name: golangci-lint
	uses: golangci/golangci-lint-action@v3

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