Fix part of #5134: Add tests to  core_storage_story (#5644)
Fix part of #5134: Add tests to  core_storage_story (#5644)

* Add story model tests

fix linting on push

fix linting on push

fix linting on push

fix linting befor import order on push

fix hanging indent  on push

fix hanging indent  on push

* Add get_by_id for story model

Fix linting issue on push

Fix linting issue on push

* Add finction doc strings to tests in story

* Add finction doc strings to tests in story and fix linting errors on push

* Fix doc srting error on push

* append model to variable name

* append model to variable name

* append model to variable name

* Fix linting error in travis

* Add new line

oppia/oppia,prasanna08/oppia,souravbadami/oppia,kevinlee12/oppia,brianrodri/oppia,prasanna08/oppia,kevinlee12/oppia,kevinlee12/oppia,souravbadami/oppia,brianrodri/oppia,oppia/oppia,brianrodri/oppia,oppia/oppia,oppia/oppia,prasanna08/oppia,oppia/oppia,brianrodri/oppia,prasanna08/oppia,brianrodri/oppia,souravbadami/oppia,souravbadami/oppia,kevinlee12/oppia,prasanna08/oppia,kevinlee12/oppia,souravbadami/oppia