Method handler

packages/vue/src/commander.ts:3203–3209

(arg: any, ctx: any)

        const rawHandler = toRawHandler(fn)
        const handler = (arg: any, ctx: any) => {
          let current: any = rawHandler(arg, ctx)
          for (const combinator of combinators) {
            current = combinator(current, arg, ctx)
          }
          return toFinalStream(current)
        }

        return this.makeStreamCommand(id, options, errorDef)(handler)
      },