Python: Misunderstanding about how imports work

Here is my loader class, ItemLoader.py:

from google.appengine.ext import db
from google.appengine.tools import bulkloader
import models

class ItemLoader(bulkloader.Loader):
    def __init__(self):
        bulkloader.Loader.__init__(self, 'Item', [('CSIN', int), # not too DRY...
                                                  ('name', str),
                                                  ('price', int),
                                                  ('quantity', int)
                                                  ]
                                   )

loaders = [ItemLoader]

Here is my kind implementation, models.py:

from google.appengine.ext import db

class Item(db.Model):
    CSIN = db.IntegerProperty()
    name = db.StringProperty()
    price = db.IntegerProperty() # OK that it's an int?
    quantity = db.IntegerProperty()

These are essentially copied from GAE instructions. When I run appcfg.py, I get this error:

ImportError: No module named models

What am I doing wrong? If I take out that import statement, I get a different error:

... No implementation for kind 'Item'

UPDATE 1: I tried copy/pasting directly from Google's instructions, and I get that same import error.

UPDATE 2: Changed the name of the kind implementation to models.py. Still doesn't work. Both ItemLoader.py and models.py are in the same directory.

UPDATE 3: hacky solution: put them both in the same file! It works, but what am I not understanding about import开发者_运维问答s?

You must add models directory to the PYTHONPATH. From docs:

(which is in your PYTHONPATH, such as the directory where you'll run the tool)

If you don't do that, python can't find your module.