Lists of reserved barewords and symbol names
B::Keywords supplies seven arrays of keywords: @Scalars, @Arrays,
@Hashes, @Filehandles, @Symbols, @Functions and @Barewords. The @Symbols
array includes the contents of each of @Scalars, @Arrays, @Hashes and
@Filehandles. Similarly, @Barewords adds a few non-function keywords
(like __DATA__, NULL) to the @Functions array.