Closure in Go, C#, Objective-C, Javascript and so on

A closure is a function value that references variables from outside its body.

Closure in GO: https://tour.golang.org/moretypes/25

Closure in C#:

1. http://blog.darkthread.net/post-2009-12-25-closure-in-c.aspx
2. http://stackoverflow.com/questions/9591476/are-lambda-expressions-in-c-sharp-closures

Closure in Objective-C(need to set __block): http://riddleapple.logdown.com/posts/220371-objetive-c-note-the-block

Closure in JavaScript: http://www.w3schools.com/js/js_function_closures.asp