Use comparison by reference for bool type objects

[czgdp1807]

Description of the problem

Currently there are many places in the code base which use == and != while comparing bool type objects.
Replace all such occurrences of == <bool-type-object> with is <bool-type-object> and != <bool-type-object> with is not <bool-type-object>. For example, == None with is None and != None with is not None.

Example of the problem

References/Other comments

[1] https://dbader.org/blog/difference-between-is-and-equals-in-python