`echo foo`
`echo #{user_input}`
`grep hosts /private/etc/* 2>&1`

%x[ ls ]
%x{ ls }
%x<ls -al #{dir}>

%x!foo #{ 42 }!
%x(foo #{ 42 })
%x{foo #{ 42 }}
%x[foo #{ 42 }]
%x<foo #{ 42 }>

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

[
	["command-literal", [
		["command", "`echo foo`"]
	]],
	["command-literal", [
		["command", "`echo "],
		["interpolation", [
			["delimiter", "#{"],
			["content", ["user_input"]],
			["delimiter", "}"]
		]],
		["command", "`"]
	]],
	["command-literal", [
		["command", "`grep hosts /private/etc/* 2>&1`"]
	]],

	["command-literal", [
		["command", "%x[ ls ]"]
	]],
	["command-literal", [
		["command", "%x{ ls }"]
	]],
	["command-literal", [
		["command", "%x<ls -al "],
		["interpolation", [
			["delimiter", "#{"],
			["content", ["dir"]],
			["delimiter", "}"]
		]],
		["command", ">"]
	]],

	["command-literal", [
		["command", "%x!foo "],
		["interpolation", [
			["delimiter", "#{"],
			["content", [
				["number", "42"]
			]],
			["delimiter", "}"]
		]],
		["command", "!"]
	]],
	["command-literal", [
		["command", "%x(foo "],
		["interpolation", [
			["delimiter", "#{"],
			["content", [
				["number", "42"]
			]],
			["delimiter", "}"]
		]],
		["command", ")"]
	]],
	["command-literal", [
		["command", "%x{foo "],
		["interpolation", [
			["delimiter", "#{"],
			["content", [
				["number", "42"]
			]],
			["delimiter", "}"]
		]],
		["command", "}"]
	]],
	["command-literal", [
		["command", "%x[foo "],
		["interpolation", [
			["delimiter", "#{"],
			["content", [
				["number", "42"]
			]],
			["delimiter", "}"]
		]],
		["command", "]"]
	]],
	["command-literal", [
		["command", "%x<foo "],
		["interpolation", [
			["delimiter", "#{"],
			["content", [
				["number", "42"]
			]],
			["delimiter", "}"]
		]],
		["command", ">"]
	]]
]
