Question about import P.S. 1.6

[sooroos]

Hi,

 

i am looking in AdminImportController to understand how the entities are imported via CSV. What i dont find are the add() and update() functions

 

For example in customerImport() function, on a sucessfull import we have $customer->add() and $customer->update().

 

I need to know/see what these functions do, where are they? Can someone tell me where should i look for?

 

P.S. 1.6.1.14