We can then use get_parameter_timeseries() to retrieve the template parameter 'denomination'. This is a helper function on the Vault object that, given the name of a parameter, returns its timeseries. We can then retrieve the most recent value of this parameter time series using .latest() or the value at a specific timestamp using .at(timestamp=required_time). We must also use the requires decorator. This decorator allows us to request Vault to prefetch only the relevant data, optimising our contract. In our example, we need to have access to the parameters, so the pre_posting_code hook should look like the following: