Abstract: I welcome you to the fourth issue of the IEEE Communications Surveys and Tutorials in 2021. This issue includes 23 papers covering different aspects of communication networks. In particular, ...

Within each content area, there are one or more tutorials. Each tutorial consists of lessons. Each lesson should be a page detailing the concept being taught, along with sample code. Lesson and page ...

Elisp is a lisp-2 with user-defined macros. A simple parser cannot detect if e.g. (foo (let ...)) is a function call with a let expression argument, or a macro call where let means something else.

Normally multiple values are not used. Special forms are required both to produce multiple values and to receive them. If the caller of a function does not request multiple values, but the called ...

This returns the sum of the arguments. If there are no arguments, the result is 0, which is an identity for this operation.