Weird Function Declaration

[Jack41EL]

I was reading Direct2D documentation, and I saw a function with the following prototype.

  ColorF(FLOAT, FLOAT, FLOAT, FLOAT)(
   FLOAT red,
   FLOAT green,
   FLOAT blue,
   FLOAT alpha = 1.0);

In this declaration, what is the purpose of the first pair of parentheses? I am unfamiliar with this syntax, and would like to know what it does.

[Hippogriff]

https://social.msdn.microsoft.com/Forums/windowsserver/en-US/fb220469-3f91-40d8-b574-678abb3abb62/colorf-class-constructor-weird-form?forum=vclanguage

"They aren't valid but this is just an issue with the documentation, the actual code lacks the first set of parenthesis so it is correct."