inline links flat

Valid links:

this is a link this is a link this is a link

escape test escape test ]]]]]]]]]]]]]]]]

Invalid links:

[this is not a link

[this is not a link](

[this is not a link](http://something.example.com/foo/bar 'test'

[this is not a link](((((((((((((((((((((((((((((((((((((((((((((((

[this is not a link]((((((((((()))))))))) (((((((((()))))))))))