How to call mysql stored proc using session in sqlalchemy

Based on the sqlalchemy it stated that:

Its important to note that when using the SQLAlchemy ORM, these objects are not generally accessed; instead, the Sessionobject is used as the interface to the database.

So i have basic/simple model class, and i have another class with model class inside as attr. As follow:

Class Test (object):
    Model = ModelClass ()

    Def __init__(self):
        Pass

    Def call_proc (self, proc, param):
        # how?
        Pass

Questions: How i call stored procedure from test class using session that i have in my model class?