''
'foo'
'foo\
bar'
""
"foo"
"foo\
bar"
"foo #{interpolation} bar"
''''''
'''foo'''
'''foo
bar'''

""""""
"""foo"""
"""foo
bar"""
"""foo #{interpolation} bar"""
"foo # comment bar"
'foo # bar'
"""foo
#comment
bar"""
'''foo
#comment
bar'''

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

[
	["string", "''"],
	["string", "'foo'"],
	["string", "'foo\\\r\nbar'"],
	["string", ["\"\""]],
	["string", ["\"foo\""]],
	["string", ["\"foo\\\r\nbar\""]],
	["string", [
		"\"foo ",
		["interpolation", "#{interpolation}"],
		" bar\""
	]],

	["multiline-string", "''''''"],
	["multiline-string", "'''foo'''"],
	["multiline-string", "'''foo\r\nbar'''"],
	["multiline-string", ["\"\"\"\"\"\""]],
	["multiline-string", ["\"\"\"foo\"\"\""]],
	["multiline-string", ["\"\"\"foo\r\nbar\"\"\""]],
	["multiline-string", [
		"\"\"\"foo ",
		["interpolation", "#{interpolation}"],
		" bar\"\"\""
	]],
	["string", ["\"foo # comment bar\""]],
	["string", "'foo # bar'"],
	["multiline-string", ["\"\"\"foo\r\n#comment\r\nbar\"\"\""]],
	["multiline-string", "'''foo\r\n#comment\r\nbar'''"]
]

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

Checks for single-line and multi-line strings and block strings.
Also checks for string interpolation inside double-quoted strings.