[Serusers] from header as append_hf() param

[caio]

Hi all,

Is it possible to add the current from header (%fu or $fu) or contact 
header as parameter of the append_hf textops function?

I need to add a custom header like the following:

	append_hf("P-Asserted-Identity: \"Caller guy\" <%fu>);

Result:

	...P-Asserted-Identity: "Caller guy" <123 at 10.3.23.5>)

There is an "append_urihf()" but it adds as prefix or suffix the R-URI 
address.

Important, SER version 0.9.7.

Regards,
Claudio