Hello @jorisvandenbossche! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/core/frame.py !

• There are no PEP8 issues in the file pandas/core/internals/blocks.py !

• In the file pandas/core/internals/managers.py, following are the PEP8 issues :

Line 744:17: E731 do not assign a lambda expression, use a def
Line 746:17: E731 do not assign a lambda expression, use a def
Line 1895:5: E731 do not assign a lambda expression, use a def
Line 1924:9: E731 do not assign a lambda expression, use a def

• In the file pandas/core/ops.py, following are the PEP8 issues :

Line 1055:9: E731 do not assign a lambda expression, use a def
Line 1057:9: E731 do not assign a lambda expression, use a def
Line 1188:80: E501 line too long (80 > 79 characters)
Line 1593:5: E731 do not assign a lambda expression, use a def
Line 1594:5: E731 do not assign a lambda expression, use a def
Line 1611:13: E731 do not assign a lambda expression, use a def
Line 1623:13: E731 do not assign a lambda expression, use a def

• There are no PEP8 issues in the file pandas/tests/frame/test_arithmetic.py !

• In the file pandas/tests/frame/test_operators.py, following are the PEP8 issues :

Line 796:9: E741 ambiguous variable name 'l'