code: function (target, cb) {
        if(!target) return cb(new Error('WebBoot.prune: size to clear must be provided'))
        var cleared = 0, remove = []
        
        function clear () {
          var n = remove.length
          while(remove.length) store.rm(remove.shift(), function () {
            if(--n) return
            if(cleared < target)
              cb(new Error('could not clear requested space'), cleared)
            else
              cb(null, cleared)
          })
        }
  
        store.ls(function (err, ls) {
          if(err) return cb(err)
          log.unfiltered(function (err, unfiltered) {
            if(err) return cb(err)
            var stored = unfiltered.reverse()
            ls.forEach(function (a) {
              if(!unfiltered.find(function (b) {
                return a.id == b.id
              })) {
                cleared += a.size
                remove.push(a.id)
              }
            })
  
            for(var i = 0; i < stored.length; i++) {
              var id = stored[i].value
              var item = ls.find(function (e) {
                return e.id === id
              })
              
              if(item) {
                cleared += item.size
                remove.push(id)
                if(cleared >= target) return clear()
              }
            }
            clear()
          })
        })
      }
docs: clear target amount of space.