GammaPrior Class
      
      GammaPrior-class.RdA class for defining gamma priors to be translated to Stan code.
Objects of class GammaPrior should not be created directly but by
the constructor gamma_prior().
Slots
- stan_code
- character. Stan implementation of the prior, with placeholders for gamma stan function parameters surrounded with - {{and- }}to be replaced with- glue::glue().
- n_param
- integer. Number of prior parameters (2). 
- constraint
- character. Support of prior distribution, - "<lower=0>".
- alpha
- numeric. Shape (>0). 
- beta
- numeric. Inverse scale (>=0).