Return a key for use when checking consistency of this update with other updates.
Return a key for use when checking consistency of this update with other updates. Must uniquely determine the state that is being updated.
Perform this update.
Perform this update.
Convert to string representation.
Convert to string representation. Really only used when printing inconsistent state exceptions.
Return the value to which the state is being updated.
Return the value to which the state is being updated.
An update of a scalar item of state
s
to have the valuet
.