Use query.get() to access objects by PK

From the SqlAlchemy docs:

"get() is special in that it provides direct access to the identity map of the owning Session. If the given primary key identifier is present in the local identity map, the object is returned directly from this collection and no SQL is emitted, unless the object has been marked fully expired. If not present, a SELECT is performed in order to locate the object."

Source: http://docs.sqlalchemy.org/en/rel_0_7/orm/query.html

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