old_contents: import likelihood, spline, age_groups, priors, covariates, process
  from process import age_specific_rate, consistent
  from covariates import predict_for
  
  
  
new_contents: import likelihood, spline, age_groups, priors, covariates, process
  from process import age_specific_rate as asr, consistent
  from covariates import predict_for
  
  
  
subject: change name of age standardized rate model to model.asr