Flags for regular expression and match last line nodes.
Constants
n - forces the ASCII-8BIT encoding
e - forces the EUC-JP encoding
x - ignores whitespace and allows comments in regular expressions
internal bytes forced the encoding to binary
internal bytes forced the encoding to US-ASCII
internal bytes forced the encoding to UTF-8
i - ignores the case of characters when matching
m - allows $ to match the end of lines within strings
o - only interpolates values into the regular expression once
u - forces the UTF-8 encoding
s - forces the Windows-31J encoding