https://www.kaggle.com/archit9406/customer-transaction-dataset
1.Understand what is cohort and cohort analysis
2.Handling missing values
3.Month extraction from date
4.Assign cohort to each transaction
5.Assigning cohort Index to each transaction
6.Calculate the number of unique customers in each group
7.Create cohort table for retention rate
8.Visualize the cohort table using the heatmap
9.Interpret the retention rate