Improve verify reliability
Improve verify reliability

`Kitchen.verify(_:)` wasn't fully thread safe.

toshi0383/TVMLKitchen,toshi0383/TVMLKitchen,Wei-Xia/TVMLKitchen,Wei-Xia/TVMLKitchen,Wei-Xia/TVMLKitchen,toshi0383/TVMLKitchen,toshi0383/TVMLKitchen,Wei-Xia/TVMLKitchen