Access to member %r before its definition line %s
Used when an instance member is accessed before it's actually assigned.
This message belongs to the classes checker.
An example for such a situation is an instance attribute in __init__() that is read before it was initialized. This includes usage of the += operator on an uninitialized instance attribute. See also E0601 for uninitialized variables that are not instance attributes, or E1101 for entirely undefined members.