r all subsequent
statements. Thus a variable declared in the transformed data block
may be used in the model block. But a variable declared in the
generated quantities block may not be used in any earlier block,
including the model block. The exception to this rule is that
variables declared in the model block are always local to the model
block and may not be accessed in the generated quantities block; to
make a variable accessible in the model and generated quantities
block, it must be declared as a trans