I2C_Anything and struct

I came across Nick Gammon's I2C_Anything.h library, and wondered if I can use this library to send a struct over I2C.
If so, what would be the code for sending and for receiving.
if not, any suggestion how to send a struct over I2C?
Thanks in advance!

Follow up: I now know I can use the struct inside I2C_Anything.h
I got it working between two Arduino Uno's, however not between an Uno as master and a NodeMCU as slave.
Anyone has an idea what can be wrong?

Try a single byte first. Can the NodeMCU be a Slave ?