make equivalent for looking in the list of values

[Ruslan Mahmatkhanov]

Hi.

For example, there is a variable in Makefile:

ALLOWED_FORMATS=html pdf-a4 pdf-letter text

How could I check that the value `epub' is not belongs to this values 
list in terms of make(1).

Need something like this (in terms of python):

if 'epub' not in ALLOWED_FORMATS:
   ...
   ...

but for make(1). I checked manpage and wasn't be able to find something 
like this at glance. It can be done with `.for' I think, but I didn't 
like it much.

Thanks in advance.

-- 
Regards,
Ruslan

Tinderboxing kills... the drives.