diff --git a/grammar.js b/grammar.js
index a8c1610..9d072d5 100644
--- a/grammar.js
+++ b/grammar.js
@@ -1,364 +1,332 @@
 module.exports = grammar({
-		name: 'dockerfile',
+  name: "dockerfile",
 
-		extras: $ => [
-			$.comment,
-			/\s+/,
-			'\\\n'
-		],
+  extras: ($) => [$.comment, /\s+/, "\\\n"],
 
-		rules: {
-				source_file: $ => repeat(seq($._instruction, "\n")),
+  rules: {
+    source_file: ($) => repeat(seq($._instruction, "\n")),
 
-				_instruction: $ => choice(
-						$.from_instruction,
-						$.run_instruction,
-						$.cmd_instruction,
-						$.label_instruction,
-						$.expose_instruction,
-						$.env_instruction,
-						$.add_instruction,
-						$.copy_instruction,
-						$.entrypoint_instruction,
-						$.volume_instruction,
-						$.user_instruction,
-						$.workdir_instruction,
-						$.arg_instruction,
-						$.onbuild_instruction,
-						$.stopsignal_instruction,
-						$.healthcheck_instruction,
-						$.shell_instruction,
-						$.maintainer_instruction,
-						$.cross_build_instruction,
-				),
+    _instruction: ($) =>
+      choice(
+        $.from_instruction,
+        $.run_instruction,
+        $.cmd_instruction,
+        $.label_instruction,
+        $.expose_instruction,
+        $.env_instruction,
+        $.add_instruction,
+        $.copy_instruction,
+        $.entrypoint_instruction,
+        $.volume_instruction,
+        $.user_instruction,
+        $.workdir_instruction,
+        $.arg_instruction,
+        $.onbuild_instruction,
+        $.stopsignal_instruction,
+        $.healthcheck_instruction,
+        $.shell_instruction,
+        $.maintainer_instruction,
+        $.cross_build_instruction
+      ),
 
-				from_instruction: $ => seq(
-						alias(/[fF][rR][oO][mM]/, "FROM"),
-						$._non_newline_whitespace,
-						optional($.param),
-						$.image_spec,
-						optional(seq(
-								alias(/[aA][sS]/, "AS"),
-								field("as", $.image_alias),
-						)),
-				),
+    from_instruction: ($) =>
+      seq(
+        alias(/[fF][rR][oO][mM]/, "FROM"),
+        $._non_newline_whitespace,
+        optional($.param),
+        $.image_spec,
+        optional(seq(alias(/[aA][sS]/, "AS"), field("as", $.image_alias)))
+      ),
 
-				run_instruction: $ => seq(
-						alias(/[rR][uU][nN]/, "RUN"),
-						$._non_newline_whitespace,
-						choice(
-								$.string_array,
-								$.shell_command,
-						),
-				),
+    run_instruction: ($) =>
+      seq(
+        alias(/[rR][uU][nN]/, "RUN"),
+        $._non_newline_whitespace,
+        choice($.string_array, $.shell_command)
+      ),
 
-				cmd_instruction: $ => seq(
-						alias(/[cC][mM][dD]/, "CMD"),
-						$._non_newline_whitespace,
-						choice(
-								$.string_array,
-								$.shell_command,
-						),
-				),
+    cmd_instruction: ($) =>
+      seq(
+        alias(/[cC][mM][dD]/, "CMD"),
+        $._non_newline_whitespace,
+        choice($.string_array, $.shell_command)
+      ),
 
-				label_instruction: $ => seq(
-						alias(/[lL][aA][bB][eE][lL]/, "LABEL"),
-						$._non_newline_whitespace,
-						repeat1($.label_pair),
-				),
+    label_instruction: ($) =>
+      seq(
+        alias(/[lL][aA][bB][eE][lL]/, "LABEL"),
+        $._non_newline_whitespace,
+        repeat1($.label_pair)
+      ),
 
-				expose_instruction: $ => seq(
-						alias(/[eE][xX][pP][oO][sS][eE]/, "EXPOSE"),
-						repeat1(choice($.expose_port, $.expansion)),
-				),
+    expose_instruction: ($) =>
+      seq(
+        alias(/[eE][xX][pP][oO][sS][eE]/, "EXPOSE"),
+        repeat1(choice($.expose_port, $.expansion))
+      ),
 
-				env_instruction: $ => seq(
-						alias(/[eE][nN][vV]/, "ENV"),
-						$._non_newline_whitespace,
-						choice(
-							repeat1($.env_pair),
-							alias($._spaced_env_pair, $.env_pair),
-						)
-				),
+    env_instruction: ($) =>
+      seq(
+        alias(/[eE][nN][vV]/, "ENV"),
+        $._non_newline_whitespace,
+        choice(repeat1($.env_pair), alias($._spaced_env_pair, $.env_pair))
+      ),
 
-				add_instruction: $ => seq(
-						alias(/[aA][dD][dD]/, "ADD"),
-						$._non_newline_whitespace,
-						optional($.param),
-						$.path,
-						$._non_newline_whitespace,
-						$.path,
-				),
+    add_instruction: ($) =>
+      seq(
+        alias(/[aA][dD][dD]/, "ADD"),
+        $._non_newline_whitespace,
+        optional($.param),
+        $.path,
+        $._non_newline_whitespace,
+        $.path
+      ),
 
-				copy_instruction: $ => seq(
-						alias(/[cC][oO][pP][yY]/, "COPY"),
-						$._non_newline_whitespace,
-						optional($.param),
-						$.path,
-						$._non_newline_whitespace,
-						$.path,
-				),
+    copy_instruction: ($) =>
+      seq(
+        alias(/[cC][oO][pP][yY]/, "COPY"),
+        $._non_newline_whitespace,
+        optional($.param),
+        $.path,
+        $._non_newline_whitespace,
+        $.path
+      ),
 
-				entrypoint_instruction: $ => seq(
-						alias(/[eE][nN][tT][rR][yY][pP][oO][iI][nN][tT]/, "ENTRYPOINT"),
-						$._non_newline_whitespace,
-						choice(
-								$.string_array,
-								$.shell_command,
-						),
-				),
+    entrypoint_instruction: ($) =>
+      seq(
+        alias(/[eE][nN][tT][rR][yY][pP][oO][iI][nN][tT]/, "ENTRYPOINT"),
+        $._non_newline_whitespace,
+        choice($.string_array, $.shell_command)
+      ),
 
-				volume_instruction: $ => seq(
-						alias(/[vV][oO][lL][uU][mM][eE]/, "VOLUME"),
-						$._non_newline_whitespace,
-						choice(
-								$.string_array,
-								seq(
-									$.path,
-									repeat(seq($._non_newline_whitespace, $.path)),
-								),
-						),
-				),
+    volume_instruction: ($) =>
+      seq(
+        alias(/[vV][oO][lL][uU][mM][eE]/, "VOLUME"),
+        $._non_newline_whitespace,
+        choice(
+          $.string_array,
+          seq($.path, repeat(seq($._non_newline_whitespace, $.path)))
+        )
+      ),
 
-				user_instruction: $ => seq(
-						alias(/[uU][sS][eE][rR]/, "USER"),
-						$._non_newline_whitespace,
-						field("user", alias($._user_name_group, $.unquoted_string)),
-						optional(seq(
-							token.immediate(":"),
-							field("group", alias($._user_name_group, $.unquoted_string)),
-						)),
-				),
+    user_instruction: ($) =>
+      seq(
+        alias(/[uU][sS][eE][rR]/, "USER"),
+        $._non_newline_whitespace,
+        field("user", alias($._user_name_group, $.unquoted_string)),
+        optional(
+          seq(
+            token.immediate(":"),
+            field("group", alias($._user_name_group, $.unquoted_string))
+          )
+        )
+      ),
 
-				_user_name_group: $ => repeat1(choice(
-					token.immediate(/[a-z][-a-z0-9_]*/),
-					$.expansion,
-				)),
+    _user_name_group: ($) =>
+      repeat1(choice(token.immediate(/[a-z][-a-z0-9_]*/), $.expansion)),
 
-				workdir_instruction: $ => seq(
-						alias(/[wW][oO][rR][kK][dD][iI][rR]/, "WORKDIR"),
-						$._non_newline_whitespace,
-						$.path,
-				),
+    workdir_instruction: ($) =>
+      seq(
+        alias(/[wW][oO][rR][kK][dD][iI][rR]/, "WORKDIR"),
+        $._non_newline_whitespace,
+        $.path
+      ),
 
-				arg_instruction: $ => seq(
-						alias(/[aA][rR][gG]/, "ARG"),
-						$._non_newline_whitespace,
-						field("name", alias(/[a-zA-Z0-9_]+/, $.unquoted_string)),
-						optional(seq(
-							token.immediate("="),
-							field("default", choice(
-								$.double_quoted_string,
-								$.unquoted_string,
-							)),
-						)),
-				),
+    arg_instruction: ($) =>
+      seq(
+        alias(/[aA][rR][gG]/, "ARG"),
+        $._non_newline_whitespace,
+        field("name", alias(/[a-zA-Z0-9_]+/, $.unquoted_string)),
+        optional(
+          seq(
+            token.immediate("="),
+            field("default", choice($.double_quoted_string, $.unquoted_string))
+          )
+        )
+      ),
 
-				onbuild_instruction: $ => seq(
-						alias(/[oO][nN][bB][uU][iI][lL][dD]/, "ONBUILD"),
-						$._non_newline_whitespace,
-						$._instruction,
-				),
+    onbuild_instruction: ($) =>
+      seq(
+        alias(/[oO][nN][bB][uU][iI][lL][dD]/, "ONBUILD"),
+        $._non_newline_whitespace,
+        $._instruction
+      ),
 
-				stopsignal_instruction: $ => seq(
-						alias(/[sS][tT][oO][pP][sS][iI][gG][nN][aA][lL]/, "STOPSIGNAL"),
-						$._non_newline_whitespace,
-						$._stopsignal_value,
-				),
+    stopsignal_instruction: ($) =>
+      seq(
+        alias(/[sS][tT][oO][pP][sS][iI][gG][nN][aA][lL]/, "STOPSIGNAL"),
+        $._non_newline_whitespace,
+        $._stopsignal_value
+      ),
 
-				_stopsignal_value: $ => repeat1(choice(
-						/[A-Z0-9]+/,
-						$.expansion,
-				)),
+    _stopsignal_value: ($) => repeat1(choice(/[A-Z0-9]+/, $.expansion)),
 
-				healthcheck_instruction: $ => seq(
-						alias(/[hH][eE][aA][lL][tT][hH][cC][hH][eE][cC][kK]/, "HEALTHCHECK"),
-						$._non_newline_whitespace,
-						choice(
-							"NONE",
-							seq(
-								repeat($.param),
-								$.cmd_instruction,
-							),
-						),
-				),
+    healthcheck_instruction: ($) =>
+      seq(
+        alias(/[hH][eE][aA][lL][tT][hH][cC][hH][eE][cC][kK]/, "HEALTHCHECK"),
+        $._non_newline_whitespace,
+        choice("NONE", seq(repeat($.param), $.cmd_instruction))
+      ),
 
-				shell_instruction: $ => seq(
-						alias(/[sS][hH][eE][lL][lL]/, "SHELL"),
-						$._non_newline_whitespace,
-						$.string_array,
-				),
+    shell_instruction: ($) =>
+      seq(
+        alias(/[sS][hH][eE][lL][lL]/, "SHELL"),
+        $._non_newline_whitespace,
+        $.string_array
+      ),
 
-				maintainer_instruction: $ => seq(
-						alias(/[mM][aA][iI][nN][tT][aA][iI][nN][eE][rR]/, "MAINTAINER"),
-						/.*/,
-				),
+    maintainer_instruction: ($) =>
+      seq(
+        alias(/[mM][aA][iI][nN][tT][aA][iI][nN][eE][rR]/, "MAINTAINER"),
+        /.*/
+      ),
 
-				cross_build_instruction: $ => seq(
-						alias(/[cC][rR][oO][sS][sS]_[bB][uU][iI][lL][dD][a-zA-Z_]*/, "CROSS_BUILD"),
-						/.*/,
-				),
-				
-				path: $ => seq(
-					choice(
-						/[^-\s\$]/, // cannot start with a '-' to avoid conflicts with params
-						$.expansion,
-					),
-					repeat(choice(
-						/[^\s\$]+/,
-						$.expansion,
-					)),
-				),
+    cross_build_instruction: ($) =>
+      seq(
+        alias(
+          /[cC][rR][oO][sS][sS]_[bB][uU][iI][lL][dD][a-zA-Z_]*/,
+          "CROSS_BUILD"
+        ),
+        /.*/
+      ),
 
-				expansion: $ => seq(
-					'$',
-					choice(
-						$.variable,
-						seq('{', alias(/[^\}]+/, $.variable), '}'),
-					)
-				),
+    path: ($) =>
+      seq(
+        choice(
+          /[^-\s\$]/, // cannot start with a '-' to avoid conflicts with params
+          $.expansion
+        ),
+        repeat(choice(/[^\s\$]+/, $.expansion))
+      ),
 
-				variable: $ => /[a-zA-Z][a-zA-Z0-9_]*/,
+    expansion: ($) =>
+      seq("$", choice($.variable, seq("{", alias(/[^\}]+/, $.variable), "}"))),
 
-				env_pair: $ => seq(
-					field("name", $._env_key),
-					token.immediate("="),
-					field("value", choice(
-						$.double_quoted_string,
-						$.unquoted_string,
-					)),
-				),
+    variable: ($) => /[a-zA-Z][a-zA-Z0-9_]*/,
 
-				_spaced_env_pair: $ => seq(
-					field("name", $._env_key),
-					token.immediate(/\s+/),
-					field("value", choice(
-						$.double_quoted_string,
-						$.unquoted_string,
-					)),
-				),
+    env_pair: ($) =>
+      seq(
+        field("name", $._env_key),
+        token.immediate("="),
+        field("value", choice($.double_quoted_string, $.unquoted_string))
+      ),
 
-				_env_key: $ => alias(/[a-zA-Z][a-zA-Z0-9_]*[a-zA-Z0-9]/, $.unquoted_string),
+    _spaced_env_pair: ($) =>
+      seq(
+        field("name", $._env_key),
+        token.immediate(/\s+/),
+        field("value", choice($.double_quoted_string, $.unquoted_string))
+      ),
 
-				expose_port: $ => seq(
-					/\d+/,
-					optional(choice(
-						"/tcp",
-						"/udp",
-					)),
-				),
+    _env_key: ($) =>
+      alias(/[a-zA-Z][a-zA-Z0-9_]*[a-zA-Z0-9]/, $.unquoted_string),
 
-				label_pair: $ => seq(
-					field("key", alias(/[-a-zA-Z0-9\._]+/, $.unquoted_string)),
-					token.immediate("="),
-					field("value", choice(
-						$.double_quoted_string,
-						$.unquoted_string,
-					)),
-				),
+    expose_port: ($) => seq(/\d+/, optional(choice("/tcp", "/udp"))),
 
-				image_spec: $ => seq(
-						field("name", $.image_name),
-						seq(
-								field("tag", optional($.image_tag)),
-								field("digest", optional($.image_digest)),
-						),
-				),
+    label_pair: ($) =>
+      seq(
+        field("key", alias(/[-a-zA-Z0-9\._]+/, $.unquoted_string)),
+        token.immediate("="),
+        field("value", choice($.double_quoted_string, $.unquoted_string))
+      ),
 
-				image_name: $ => repeat1(choice(
-					token.immediate(/[^@:\s\$]+/),
-					$.expansion,
-				)),
+    image_spec: ($) =>
+      seq(
+        field("name", $.image_name),
+        seq(
+          field("tag", optional($.image_tag)),
+          field("digest", optional($.image_digest))
+        )
+      ),
 
-				image_tag: $ => seq(
-						token.immediate(":"),
-						repeat1(choice(
-							token.immediate(/[^@\s\$]+/),
-							$.expansion,
-						))
-				),
+    image_name: ($) =>
+      repeat1(choice(token.immediate(/[^@:\s\$]+/), $.expansion)),
 
-				image_digest: $ => seq(
-						token.immediate("@"),
-						repeat1(choice(
-							token.immediate(/[a-zA-Z0-9:]+/),
-							$.expansion,
-						)),
-				),
+    image_tag: ($) =>
+      seq(
+        token.immediate(":"),
+        repeat1(choice(token.immediate(/[^@\s\$]+/), $.expansion))
+      ),
 
-				param: $ => seq(
-						"--",
-						field("name", token.immediate(/[a-z][-a-z]*/)),
-						token.immediate("="),
-						field("value", token.immediate(/[^\s]+/)),
-				),
+    image_digest: ($) =>
+      seq(
+        token.immediate("@"),
+        repeat1(choice(token.immediate(/[a-zA-Z0-9:]+/), $.expansion))
+      ),
 
-				image_alias: $ => repeat1(choice(
-					/[-a-zA-Z0-9_]+/,
-					$.expansion,
-				)),
+    param: ($) =>
+      seq(
+        "--",
+        field("name", token.immediate(/[a-z][-a-z]*/)),
+        token.immediate("="),
+        field("value", token.immediate(/[^\s]+/))
+      ),
 
-				string_array: $ => seq(
-						"[",
-						optional(seq(
-								$.double_quoted_string,
-								repeat(seq(",", $.double_quoted_string)),
-						)),
-						"]",
-				),
+    image_alias: ($) => repeat1(choice(/[-a-zA-Z0-9_]+/, $.expansion)),
 
-				shell_command: $ => seq(
-						$.shell_fragment,
-						repeat(seq(
-							$.line_continuation,
-							repeat($._comment_line),
-							$.shell_fragment,
-						)),
-				),
+    string_array: ($) =>
+      seq(
+        "[",
+        optional(
+          seq($.double_quoted_string, repeat(seq(",", $.double_quoted_string)))
+        ),
+        "]"
+      ),
 
-				shell_fragment: $ => repeat1(choice(
-					/[^\\\[\n#\s][^\\\n]*/,
-					/\\[^\n]/,
-				)),
+    shell_command: ($) =>
+      seq(
+        $.shell_fragment,
+        repeat(
+          seq($.line_continuation, repeat($._comment_line), $.shell_fragment)
+        )
+      ),
 
-				line_continuation: $ => '\\\n',
+    shell_fragment: ($) => repeat1(choice(/[^\\\[\n#\s][^\\\n]*/, /\\[^\n]/)),
 
-				_comment_line: $ => seq(
-					alias($._anon_comment, $.comment), '\n'
-				),
+    line_continuation: ($) => "\\\n",
 
-				_anon_comment: $ => seq('#', /.*/),
+    _comment_line: ($) => seq(alias($._anon_comment, $.comment), "\n"),
 
-				double_quoted_string: $ => seq(
-						'"',
-						repeat(choice(
-								token.immediate(prec(1, /[^"\n\\\$]+/)),
-								$.escape_sequence,
-								$.expansion,
-						)),
-						'"'
-				),
+    _anon_comment: ($) => seq("#", /.*/),
 
-				unquoted_string: $ => repeat1(choice(
-					token.immediate(/[^\s\n\"\\\$]+/),
-					token.immediate("\\ "),
-					$.expansion,
-				)),
+    double_quoted_string: ($) =>
+      seq(
+        '"',
+        repeat(
+          choice(
+            token.immediate(prec(1, /[^"\n\\\$]+/)),
+            $.escape_sequence,
+            $.expansion
+          )
+        ),
+        '"'
+      ),
 
-				escape_sequence: $ => token.immediate(seq(
-						'\\',
-						choice(
-								/[^xuU]/,
-								/\d{2,3}/,
-								/x[0-9a-fA-F]{2,}/,
-								/u[0-9a-fA-F]{4}/,
-								/U[0-9a-fA-F]{8}/
-						)
-				)),
+    unquoted_string: ($) =>
+      repeat1(
+        choice(
+          token.immediate(/[^\s\n\"\\\$]+/),
+          token.immediate("\\ "),
+          $.expansion
+        )
+      ),
 
-				_non_newline_whitespace: $ => /[\t ]+/,
+    escape_sequence: ($) =>
+      token.immediate(
+        seq(
+          "\\",
+          choice(
+            /[^xuU]/,
+            /\d{2,3}/,
+            /x[0-9a-fA-F]{2,}/,
+            /u[0-9a-fA-F]{4}/,
+            /U[0-9a-fA-F]{8}/
+          )
+        )
+      ),
 
-				comment: $ => seq("#", /.*/),
-		}
+    _non_newline_whitespace: ($) => /[\t ]+/,
+
+    comment: ($) => seq("#", /.*/),
+  },
 });
-