From: Robert Griesemer v was declared via var v = x.
The function Offsetof takes a (possibly parenthesized) selector
-denoting a struct field of any type and returns the field offset in bytes relative to the
-struct's address.
+s.f, denoting a field f of the struct denoted by s
+or *s, and returns the field offset in bytes relative to the struct's address.
+If f is an embedded field, it must be reachable
+without pointer indirections through fields of the struct.
For a struct s with field f: