It ensures that new price values propagated from the Oracles are not taken up by the system until a specified delay has passed.
Periodically feeds a delayed price into the system for a particular collateral type.
peek()
Returns the current feed value and a boolean indicating whether it is valid.
read()
Returns the current feed value; reverts if it was not set by some valid mechanism.
peep()
Returns the next feed value (i.e. the one that will become the current value upon the next poke()
call), and a boolean indicating whether it is valid.