mono-mcs 5.18.0.240+dfsg-3 (armhf binary) in ubuntu focal

 This is the Mono C# (C-Sharp) 2.0, 3.0, 4.0 and 5.0 compiler,
 a platform-independent compiler which produces
 CIL (Common Intermediate Language) binary executables.
 .
 This compiler targets the CLI 2.0, 4.0 or 4.5 runtime version.
 .
 The mcs compiler supports different C# versions as follows.
 With C# 2.0 it supports:
  - generics
  - iterators (yield)
  - nullable value types
  - partial types
  - anonymous methods
  - static classes
  - coalesce operator: ??
 .
 With C# 3.0 it supports:
  - Language Integrated Query (LINQ)
  - object initializers
  - collection initializers
  - anonymous types
  - local variable type inference
  - implicitly-typed arrays
  - lambda expressions
  - automatic properties
  - extension methods
  - partial methods
 .
 With C# 4.0 it supports:
  - dynamic binding (duck typing)
  - named and optional arguments
  - covariant and contravariant generic type parameters
 .
 With C# 5.0 (which is the default) it supports:
  - asynchronous methods
  - caller info attributes (as of Mono 3.0 currently not supported!)
 .
 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.