[style] Fixed inconsistent identation

Automatic cleanup with PyCharm
[style] Create dict/list as literal when possible

Automatic cleanup with PyCharm
[style] Use augmented assignment when possible

Automatic cleanup with PyCharm
[style] Simplified boolean tests

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Testing for None must use 'is'

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Default parameter must not be mutable

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Local variable possibly referenced before assignment

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Do not use the 'callable' Python keyword as arg name

Automatic cleanup with PyCharm
[style] Remove trailing semi-colons

Automatic cleanup with PyCharm