where is RestrictedBoltzmannMachines.fpcd! — Method

in the document page https://docs.juliahub.com/RestrictedBoltzmannMachines/ygJtt/0.21.1/autodocs/ There is RestrictedBoltzmannMachines.fpcd! — Method listed. but nowhere to be found in the code. Does it exist? maybe in an older version? Isn't it needed to reliably sample synthesized fantasy particles from random input?