What does "log" in feature_matrix[["MEAN_SUNDAY(log.value, datetime)", "MEAN_SUNDAY(log.value_2, datetime)"]] from featuretools mean?

Question

I have a doubt if log.value and log.value_2 is,

1) The logarithm of column "value" and "value_2" along with "datetime" is sent as two inputs to MEAN_SUNDAY to perform the user-defined function.

2) The log is just an entity from the entityset which accesses its columns "value" and "value_2".

Can you please tell me which is correct and how do I differentiate that my feature extracted is actually (1) or (2)?

Answer 1

The second interpretation is correct. The name of the entity is log.