Morris2023              Example time series data from a methane
                        dilution pool experiment.
frac_P_default          Retrieve default P fractionation value for a
                        pool
frac_k_default          Retrieve default k fractionation value for a
                        pool
pdr_cost                Cost function between observed and predicted
                        pools
pdr_estimate_k0         Estimate initial k from heavy isotope
                        concentration data
pdr_fractionation       P and k fractionation values
pdr_optimize            Optimize production and consumption parameters
                        for pool dilution data
pdr_optimize_df         Optimize production and consumption parameters
                        for pool dilution data
pdr_predict             Predict total pool, heavy isotope pool, and
                        atom percent
