`git machete github` or `go` or `show` without command don't list possible commands/directions

[PawelLipski]

$ g m show
git machete show: error: the following arguments are required: direction
$ g m go
git machete go: error: the following arguments are required: direction
$ g m github
git machete github: error: the following arguments are required: subcommand, request_id

They should also list the possible options.