float to unicode question

[gabor]

hi,

this works:
a = str(14.34)

this works:
a = unicode(14.34)

this doesn't work:
a = unicode(14.34,'iso-8859-1')

why?
i have to do:
a = unicode(string(14.34),'iso-8859-1')

of course there is no sense in specifying an encoding for a float
number, but in my program i'm dealing with all kind of data, not just
numbers, so i have to do:

a = unicode(str(something),'iso-8859-1'),
because i don't know what type something is.

the question is why does it work to convert a float to unicode without
specifying the codepage, but it fails when codepage specified?

thanks,
gabor