Model_mommy seq errors

gistfile1.py

#script.py
from heroes.mommy_recipes import make_hero

make_hero(steam_id=1)


# mommy_recipes.py
from model_mommy.recipe import Recipe, seq, foreign_key
from model_mommy import mommy

from heroes.models import Hero

my_hero = Recipe(
    Hero,
    visible=True,
    # name=seq('Hero'),
    # steam_id=seq(1),
)


def make_hero(steam_id=None):
    if steam_id is not None:
        hero = mommy.make_recipe('heroes.my_hero')
    else:
        hero = mommy.make_recipe('heroes.my_hero')
    return hero


# models.py
class Hero(models.Model):
    name = models.CharField(
        max_length=200,
        help_text="In-game name."
    )
    steam_id = models.PositiveIntegerField(
        unique=True,
    )

# uncommenting the sequences, 
# stacktrace
Traceback (most recent call last):
  File "convenience files/kernprof test.py", line 3, in <module>
    make_hero(steam_id=1)
  File "/home/me/Projects/proj/proj/proj/heroes/mommy_recipes.py", line 63, in make_hero
    hero = mommy.make_recipe('heroes.my_hero')
  File "/home/me/.virtualenvs/venv/local/lib/python2.7/site-packages/model_mommy/mommy.py", line 86, in make_recipe
    return _recipe(mommy_recipe_name).make(_quantity=_quantity, **new_attrs)
  File "/home/me/.virtualenvs/venv/local/lib/python2.7/site-packages/model_mommy/recipe.py", line 43, in make
    return mommy.make(self.model, **self._mapping(attrs))
  File "/home/me/.virtualenvs/venv/local/lib/python2.7/site-packages/model_mommy/recipe.py", line 28, in _mapping
    mapping[k] = self._iterator_backups[k][1]
KeyError: 'steam_id'