Needs to be case insenstive ([Yy])
or just an existence check [[ -v HAS_ALLOW_UNSAFE ]]

Hi I was testing the page and it's great, just one thing many times instagram appears as busy but in reality it is not, I don't know if it is a bug or something with isntagran in particular. Thank you so much.

Each assertion method should clearly document its purpose.

As the return values for each assertion method can either be the Check object instance itself or an exception and each method takes no parameter, docs are straightforward to write.

This is the first step towards having an automated documentation system - eg. see Sphinx setup on my other projects [PyOWM](https://github.com/csparpa/

Check if the current environment is Internet Explorer.

Update README.md: under is > Environment