What do I use if not `float-time'?

[Deniz Dogan]

In the documentation for `float-time' in "(elisp) Time of Day" I read
the following: "_Warning_: Since the result is floating point, it may
not be exact.  Do not use this function if precise time stamps are
required."

Okay, so what do I use instead? I just want a "UNIX timestamp" as an
integer or string. What's the idiomatic way to get that?

-- 
Deniz Dogan