libmono-cil-dev 6.8.0.105+dfsg-3.3 (amd64 binary) in ubuntu lunar

 This package contains development headers for the Mono Base Class Libraries.
 .
 Mono is a platform for running and developing applications based on the
 ECMA/ISO Standards. Mono is an open source effort led by Xamarin.
 Mono provides a complete CLR (Common Language Runtime) including compiler and
 runtime, which can produce and execute CIL (Common Intermediate Language)
 bytecode (aka assemblies), and a class library.