[#62802482] [#62996658] [#62808308] [#63112276]

[#62802482] checked with various cases for auhor_cocitations graph.
Will update the code with some updates and finish the story
[#62996658] coding completed but not marking this as 'finish' in PT
because its corresponding test cases story is not over.
[#62808308] changes made, but some parts are commented as they were
throwing few errors. will continue on monday.