handle in and not in seperately

[loechel]

In test we should check following cases seperately:

a in my_object
a in my_list
a in my_dict
a in my_set

at they might use __contains__ or something else, depending on the protocol.

[loechel]

Partial check for that issue in #132

The Check for:

a in my_object

should be handled separatly.

[loechel]

This issue is partial solved in #132 and the rest is moved to a new issue #139