[Biopython] Host_organism field in SwissProt

[bar tomas]

Hi,
I'm using BioPython for processing protein sequences from SwissProt database.
I'm following the excellent tutorial documentation on SwissProt querying (p.107)
I'm just wondering about the meaning of the field 'host_organism' in a
swissprot record, as I haven't yet found a record where the value of
this field is supplied.
If the record concerns the protein sequence of a bacteria, for
instance, does the host_organism field contain a list of taxonomic ids
of possible host organisms where the bacteria can be found?
Many thanks