libmono-system-reactive-core2.2-cil 4.2.1.102+dfsg2-7ubuntu4 (amd64 binary) in ubuntu xenial

 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.
 .
 This package contains the System.Reactive.Core library which is part
 of Reactive Extensions.