Testing character files

[Peter Wilkinson]

I have been parsing character files that use ASCII and unicode (utf_16) 
encoded.

I have written a script for converting unicode to ASCII given a directory. 
I would like the script to test that a given file _is_ the in the 'utf_16' 
format before attempting to read it, i.e. it should only convert those 
files that are unicode.

Are there any built in methods, for testing a file encoding ?

Peter