fern-mapping-collapse-or-leave
The fern plugin for mapping to collapse or leave.
mapping
Plug mapping
nmap <Plug>(fern-action-collapse-or-leave)
Default mapping
nmap <buffer><silent> h <Plug>(fern-action-collapse-or-leave)
FAQ
How to disable this plugin's default mapping?
You can set below variable to 1.
let g:fern#mapping#collapse_or_leave#disable_default_mappings = 1