CobraCore is a class within Cobra's standard library (known as "Cobra.Core"). It is immediately accessible in Cobra code and contains numerous shared methods for various utility functions.

You can browse the source online to see the method signatures along with their doc strings, contracts and unit tests: Source/Cobra.Core/CobraCore.cobra

It's not the only class in the library, which can be browsed in full at Source/Cobra.Core

See also: LibraryTopics, EncodeAndDecode