It's the 'Dynamic Dictionary' [0]. It's usually called 'parameters' but it's idiomatic in dotnet to name lambda input parameter '_' if don't use it in your expr

It's the 'Dynamic Dictionary' [0]. It's usually called 'parameters' but it's idiomatic in dotnet to name lambda input parameter '_' if don't use it in your expression. [0] https://github.com/NancyFx/Nancy/wiki/Taking-a-look-at-the-DynamicDictionary https://github.com/NancyFx/Nancy/wiki/Taking-a-look-at-the-D...