Sniffing encoding type by looking at file BOM header

[python at bdurham.com]

I assume there's no standard library function that wraps
codecs.open() to sniff a file's BOM header and open the file with
the appropriate encoding?

My reading of the docs leads me to believe that there are 5 
types of possible BOM headers with multiple names (synoymns?)
for the same BOM encoding type.

BOM          = '\xff\xfe'
BOM_LE       = '\xff\xfe'
BOM_UTF16    = '\xff\xfe'
BOM_UTF16_LE = '\xff\xfe'

BOM_BE       = '\xfe\xff'
BOM32_BE     = '\xfe\xff'
BOM_UTF16_BE = '\xfe\xff'

BOM64_BE     = '\x00\x00\xfe\xff'
BOM_UTF32_BE = '\x00\x00\xfe\xff'

BOM64_LE     = '\xff\xfe\x00\x00'
BOM_UTF32    = '\xff\xfe\x00\x00'
BOM_UTF32_LE = '\xff\xfe\x00\x00'

BOM_UTF8     = '\xef\xbb\xbf'

Is the process of writing a BOM sniffer readlly as simple 
as detecting one of these 5 header types and then calling 
codecs.open() with the appropriate encoding= parameter?

Note: I'm only interested in Unicode encodings. I am not
interested in any of the non-Unicode encodings supported 
by the codecs module.

Thank you,
Malcolm