.
Functions whose names end in <code>_lp</code> assume access to the log
probability accumulator and are only available in the transformed
parameter and model blocks. Functions whose names end in <code>_rng</code>
assume access to the random number generator and may only be used
within the generated quantities block, transformed data block, and
within user-defined functions ending in <code>_rng</code>. See
the <a href="function-bodies-section.html#function-bodies.section">section on function bodies</a> for 