Concepts
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	basic_outcome<T>A boolean concept matching types which are convertible to a basic_outcome<T, EC, EP, NoValuePolicy>.
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	basic_result<T>A boolean concept matching types which are convertible to a basic_result<T, E, NoValuePolicy>.
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	value_or_error<T>A boolean concept matching types with either a value or an error. 
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	value_or_none<T>A boolean concept matching types with an optional value. 



