'a'
'z'
'0'
'_'
'あ'
'\''         # single quote
'\\'         # backslash
'\a'         # alert
'\b'         # backspace
'\e'         # escape
'\f'         # form feed
'\n'         # newline
'\r'         # carriage return
'\t'         # tab
'\v'         # vertical tab
'\0'         # null character
'\uFFFF'     # hexadecimal unicode character
'\u{10FFFF}' # hexadecimal unicode character

----------------------------------------------------

[
	["char", "'a'"],
	["char", "'z'"],
	["char", "'0'"],
	["char", "'_'"],
	["char", "'あ'"],
	["char", "'\\''"], ["comment", "# single quote"],
	["char", "'\\\\'"], ["comment", "# backslash"],
	["char", "'\\a'"], ["comment", "# alert"],
	["char", "'\\b'"], ["comment", "# backspace"],
	["char", "'\\e'"], ["comment", "# escape"],
	["char", "'\\f'"], ["comment", "# form feed"],
	["char", "'\\n'"], ["comment", "# newline"],
	["char", "'\\r'"], ["comment", "# carriage return"],
	["char", "'\\t'"], ["comment", "# tab"],
	["char", "'\\v'"], ["comment", "# vertical tab"],
	["char", "'\\0'"], ["comment", "# null character"],
	["char", "'\\uFFFF'"], ["comment", "# hexadecimal unicode character"],
	["char", "'\\u{10FFFF}'"], ["comment", "# hexadecimal unicode character"]
]
