Using methods of a class from another in python

I'm working through 'Dive Into Python' on Google App Engine and came across this error while attempting to call one class's methods from another:

ERROR __init__.py:463] create() takes exactly 1 argument (2 given)
Traceback (most recent call last):
  File "main.py", line 35, in get
    dal.create("sample-data");
  File "dataAccess/dal.py", line 27, in create
    self.data_store.create(data_dictionary);
TypeError: create() takes exactly 1 argument (2 given)

Here's my main class:

# filename: main.py

from dataAccess.dal import DataAccess

class MySampleRequestHandler(webapp.RequestHandler):
"""Configured to be invoked for a specific GET request"""

    def get(self):
        dal = DataAccess();
        dal.create("sample-data"); # problem area

MySampleRequestHandler.get() tries to instantiate and invoke DataAccess which is defined else where:

# filename: dal.py

from dataAccess.datastore import StandardDataStore

class DataAccess:
    """Class responsible for wrapping the specific data store"""

    def __init__(self):
        self.data_store = None;

        data_store_setting = config.SETTINGS['data_store_name'];                
        if data_store_setting == DataStoreTypes.SOME_CONFIG:
            self.data_store = StandardDataStore();

        logging.info("DataAccess init completed.");

    def create(self, data_dictionary):
        # Trying to access the data_store attribute declared in __init__
        data_store.create(data_dictionary);

I thought I could call DataAccess.create() with 1 parameter for its argument, especially according to how Dive into Python notes about class method calls:

When defining your class methods, you must explicitly list self as the first argument for each method, including __init__. When you call a method of an ancestor class from within your class, you must include the self argument. But when you call your clas开发者_Go百科s method from outside, you do not specify anything for the self argument; you skip it entirely, and Python automatically adds the instance reference for you.

In self.data_store.create(data_dictionary), the self.data_store refers to the object created by self.data_store = StandardDataStore() in the __init__ method.

It looks like the create method of a StandardDataStore object doesn't expect an additional argument.

It should be self.data_store.create(data_dictionary);