pstorage example for storage data in the FLASH

I need to store a data base into an area of the FLASH. I understand I need to use the pstorage capability. All the reference I found about it , are just part of the code where the entire project is missing. For example, I need to use pstorage_init but I don't know which library it come from. the same is for pstorage_register which I don't know where it defne. 

Is there a basic project example with all the C&h files requere to make a data storage in the FLASH and simple example in the main for store it?

I use SES 4.12 with nRF5_SDK_15.2.0_9412b96.