Mixins - language feature

Example from Python, Cython:

# https://easyaspython.com/mixins-for-fun-and-profit-cb9962760556
class EssentialFunctioner(LoggerMixin, object):

Example from Ruby:

module A
   def a1
   end
   def a2
   end
end
module B
   def b1
   end
   def b2
   end
end
class Sample
include A
include B
   def s1
   end
end
samp = Sample.new
samp.a1
samp.a2
samp.b1

Example from TypeScript, Static Typescript:

// https://www.typescriptlang.org/docs/handbook/mixins.html
class SmartObject implements Disposable, Activatable {
}
// Note: still need to do some runtime ops to make that work.

Example from Julia:

# Including the same code in different modules provides mixin-like behavior.
module Normal
include("mycode.jl")
end

module Testing
include("safe_operators.jl")
include("mycode.jl")
end

Example from Racket:

(mixin (interface-expr ...) (interface-expr ...)
 class-clause ...)

Example from Xtext:

grammar org.example.domainmodel.Domainmodel
       with org.eclipse.xtext.common.Terminals

Languages with Mixins include Python, Ruby, TypeScript, Julia, Racket, Cython, Xtext, Static Typescript