class IRB::OutputMethod

def parse_printf_format(format, opts)

[diouxXeEfgGcsb%]
#(hh|h|l|ll|L|q|j|z|t)
.(\*|\*[1-9][0-9]*\$|[1-9][0-9]*|)?
(\*|\*[1-9][0-9]*\$|[1-9][0-9]*)
[#0- +]
%

+format+ from #printf
Kernel#sprintf, if there was a successful Regexp match in the given
Returns an array of the given +format+ and +opts+ to be used by 
def parse_printf_format(format, opts)
  return format, opts if $1.size % 2 == 1
end