Non-static method Gears\String\Str::contains() should not be called statically

[netizenking]

i have "gears/string": "*", in my composer.json file
In the Pdf.php file i changed use Gears\String as Str to use Gears\String\Str and now it is giving me the error:
Non-static method Gears\String\Str::contains() should not be called statically
Somebody tell me what am doing wrong. Thank you

[netizenking]

this error was being brought about by the wrong document paths