Can't be iterating directly in dictionary. So you can through converting into tuple.
first_names = ['foo', 'bar']
last_names = ['gravy', 'snowman']
fields = {
'first_names': first_names,
'last_name': last_names,
}
tup_field=tuple(fields.items())
for names in fields.items():
field,possible_values = names
tup_possible_values=tuple(possible_values)
for pvalue in tup_possible_values:
print (field + "is" + pvalue)