understing what is Spring and Binstub, instead of $bundle exec [rails_commands], it's better to use $./bin/[rails_commands] (rails_commands : rails, rspec, setup, rake, etc )
And it's even better to use direnv, since it will shorhand us to type $./bin/[rails_commands] (any executable file in ./bin), to just $[rails_commands], for example: instead of $./bin/rails s, we can just type $rails s.
$ brew install direnv