def __init__(self, filename, subclass, allow_mmap=True):
    'Store the useful information for later'
    self.filename = filename
    self.subclass = subclass
    self.allow_mmap = allow_mmap
Store the useful information for later
def __init__(self, filename, subclass, allow_mmap=True):
    
    self.filename = filename
    self.subclass = subclass
    self.allow_mmap = allow_mmap