Parameter indexing in function and gq block

[hyunjimoon]

1. which is better btw theta[2] vs alpha, beta? as function input argument?
2. could we vectorize in gq block w.o. extra td block as the solution below?

   theta_tilde[1] = normal_rng(1, 0.5); //TODO U5
   theta_tilde[3] = normal_rng(1, 0.5); //TODO U5
   theta_tilde[2] = normal_rng(0.05, 0.05); //TODO U5
   theta_tilde[4] = normal_rng(0.05, 0.05); //TODO U5

   sol. suggested in here

   
   transformed data {
   int N = 10;
   vector[N] ones_N = rep_vector(1, N);
   }

generated quantities { real yrep [N] = normal_rng(ones_N 1, ones_N 10);
}