setup composer file
require phpunit 4.1.0
setup phpunit; add first test
return input if no keys are given
return value if key is present
update test names
return null if key does not exist
return null if digging in non-array
return deep value if multiple keys are given
use an array to dig with multiple keys
return input if specific key is null
keep digging if any key is null
provide basic documentation
update readme