Lazy load of database

example:

file1.py

from LazyPony import LazyEntityMeta

class A(metaclass=LazyEntityMeta):
    id = PrimaryKey(int, auto=True)

file2.py

from LazyPony import LazyEntityMeta

db = Database()
LazyEntityMeta.attach(db)
db.bind()
db.generate_mapping()

file3.py

from file1 import A

query = A.select()