If a struct contains fields (including functions) that are declared with
autounravel, these fields will be unraveled from the struct at:
struct definition;
typedef import statement, if the struct is the argument for one of
the type parameters;
unravel or access statement that unravels the struct from
a module or outer struct (for instance,
from rational access rational; would make the + operator available
from the struct rational defined in rational.asy);
typedef statement like typedef rational.rational rat;
that renames a struct.