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Issue number(s) that this pull request fixes

• Fixes [Refactor] Implement a _GraphAlgorithmMixin class containing all the algorithms required for the other child classes such as DAG, PDAG, ADMG, etc. #2384

List of changes to the codebase in this pull request

• Write Test code
• Write code logic(_GraphAlgorithmMixin)
• Refactor _GraphAlgorithmMixin class