Meaning of the dot-function syntax

[evilrat]

On Sunday, 1 October 2023 at 08:22:48 UTC, dhs wrote:
> Hi,
>
> What's the meaning of the dot in the call to writeln() below?
>
> ```d
>     .writeln("Hello there!");
> ```
>
> I haven't found this in the spec or anywhere else. This is used 
> very often in the source code for Phobos.
>
> Thanks,
> dhs

It is either means "use global scope writeln" in cases when there 
is local writeln in the scope shadowing global one, or simply a 
chained calls like myarray.filter().sort().map() each on new line.