Present with a class that behaves like a hash causes early rendering at best and usually hard to debug errors

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A Mongoid::Criteria, for example, responds to merge, so this was required to present it. This is because of https://github.com/intridea/grape/blob/master/lib/grape/dsl/inside_route.rb#L209, clearly we need a better solution here, maybe simple by registering representable classes?

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Maybe we can refactor this with some kind of presenter registration DSL?

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Here're some examples of what I have on the rhs of present:

present self, with: PresenterClassThatDoesntCareWhatTheInstanceIs
present Mongoid::Document instance, with: PresenterClass
present Mongoid::Criteria instance, with: PresenterClass