test => missing element
refactroing => using best practice from codewars
test => return null if all in array
Merge branch 'return_the_missing_element' into master
add test into all-tests.html
test => retrieve value
test => retrieve value from right
test => out of bounds
refactoring
test => retrieve empty string
Merge branch 'retrieve_array_value_with_index_by_default' into master
add test into all-tests.html