Edits to isort and contribution instructions (#714)

Summary:
Pull Request resolved: #714

1. Add command for earlier versions of isort
2. For contributions in the `research` folder, add instructions about code fomratting.
3. Specify version of isort in dev requirements
4. Remove -v (verbose) arg since this arg seems to alter the behavior of isort in some cases.

Reviewed By: EnayatUllah

Differential Revision: D68078254

fbshipit-source-id: 21b75ade5c651cb4b890a4906afca002394e7aee

.github/workflows/ci_cpu.yml

@@ -32,7 +32,7 @@ jobs:
       - name: Lint with black
         run: black --check --diff --color .
       - name: Check import order with isort
-        run: isort -v -l 88 -o opacus --lines-after-imports 2 -m 3 --trailing-comma --check-only .
+        run: isort -l 88 -o opacus --lines-after-imports 2 -m 3 --trailing-comma --check-only .
 
   ########### UNIT TESTS ##############
   unittest_py38_torch_release:

CONTRIBUTING.md

@@ -31,11 +31,16 @@ for advanced usage).
 
 Opacus also uses [isort](https://github.com/timothycrosley/isort) to sort imports
 alphabetically and separate into sections. isort is installed easily via
-pip using `pip install isort`, and run locally by calling
+pip using `pip install isort --upgrade`, and run locally by calling
 ```bash
-isort -v -l 88 -o opacus --lines-after-imports 2 -m 3 --trailing-comma  .
+isort -l 88 -o opacus --lines-after-imports 2 -m 3 --trailing-comma  .
 ```
 from the repository root. Configuration for isort is located in .isort.cfg.
+If using `isort` versions `<5.0.0` call
+```bash
+isort -l 88 -o opacus --lines-after-imports 2 -m 3 --trailing-comma --recursive
+```
+
 
 We feel strongly that having a consistent code style is extremely important, so
 CircleCI will fail on your PR if it does not adhere to the black or flake8 formatting style or isort import ordering.
@@ -96,7 +101,7 @@ Run following command from `website` folder. It will build the docs and serve th
 ```
 
 You can also perform spell checks on documentation automatically (besides IDEs) using [```sphinxcontrib-spelling```](https://sphinxcontrib-spelling.readthedocs.io/en/latest/install.html)
-Note that you will also need [```PyEnchant```](https://pyenchant.github.io/pyenchant/) to run ```sphinxcontrib-spelling```, and thus the Enchant C library. Use this guide for ```PyEnchant```. 
+Note that you will also need [```PyEnchant```](https://pyenchant.github.io/pyenchant/) to run ```sphinxcontrib-spelling```, and thus the Enchant C library. Use this guide for ```PyEnchant```.
 
 Steps:
 1. Install the extension with pip: ```pip install sphinxcontrib-spelling```

dev_requirements.txt

@@ -8,7 +8,7 @@ flake8
 sphinx
 sphinx-autodoc-typehints
 mypy>=0.760
-isort
+isort>=5.0.0
 hypothesis
 tensorboard
 datasets

research/README.md

@@ -9,6 +9,8 @@ We warmly welcome and encourage contributions of new methods! To contribute, ple
 1. Fork the repo and create your branch from `main`.
 2. Place the new method in a separate subfolder within the `research` directory.
 3. The new folder should include a `README.md` that explains the method at a high level, demonstrates usage (e.g., introducing new parameters to the `PrivacyEngine`), and cites relevant sources. The subfolder name should aptly represent the method.
+4. Format code using `black`, `flake8`, and `isort` following the instructions under `Code Style` [here](https://github.com/pytorch/opacus/blob/main/CONTRIBUTING.md).
+5. Add copyright headers to each `.py` file contributed in the format `# Copyright (c) [copy-right holder]`.
 
 More detailed PR instructions can be found [here](https://github.com/pytorch/opacus/blob/main/CONTRIBUTING.md).