+CONSTANTS
+ "A_THREADSAFE"
+ True if and only if the module could have been built with thread-safety
+ features enabled. This constant only has a meaning when your perl is
+ threaded, otherwise it will always be false.
+
+ "A_FORKSAFE"
+ True if and only if this module could have been built with fork-safety
+ features enabled. This constant will always be true, except on Windows
+ where it is false for perl 5.10.0 and below.
+
+CAVEATS
+ The pragma doesn't apply when one dereferences the returned value of an
+ array or hash slice, as in "@array[$id]->{member}" or
+ @hash{$key}->{member}. This syntax is valid Perl, yet it is discouraged
+ as the slice is here useless since the dereferencing enforces scalar
+ context. If warnings are turned on, Perl will complain about one-element
+ slices.
+