def clean(number = nil, force = false, all = false)
      git_call "checkout #{local.target_branch}"
      local.prune_remotes
      # Determine strategy to clean.
      if all
        local.clean_all
      else
        local.clean_single(number, force)
      end
      # Remove al review remotes without existing local branches.
      local.clean_remotes
    end
def clean(number = nil, force = false, all = false)
      git_call "checkout #{local.target_branch}"
      local.prune_remotes
      # Determine strategy to clean.
      if all
        local.clean_all
      else
        local.clean_single(number, force)
      end
      # Remove al review remotes without existing local branches.
      local.clean_remotes
    end
Remove remotes with 'review' prefix (left over from previous reviews).
 Prune all existing remotes and delete obsolete branches (left over from
 already closed requests).