diff --git a/.eslintrc.json b/.eslintrc.json
index ed46161f..79fafbfe 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -9,10 +9,13 @@
     "arrow-parens": ["error", "as-needed"],
     "comma-dangle": ["error", "never"],
     "global-require": "off",
-    "no-unused-vars": ["error", {
-      "argsIgnorePattern": "^_",
-      "varsIgnorePattern": "^_"
-    }],
+    "no-unused-vars": [
+      "error",
+      {
+        "argsIgnorePattern": "^_",
+        "varsIgnorePattern": "^_"
+      }
+    ],
     "object-curly-newline": "off",
     "prefer-spread": "off",
     "quotes": "off"
diff --git a/.prettierignore b/.prettierignore
index 01989dc4..a639810c 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -2,3 +2,4 @@
 /coverage/
 /pkg/
 /vendor/
+*.js
diff --git a/.travis.yml b/.travis.yml
index 1d80f124..469609db 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,20 +1,20 @@
 language: ruby
 rvm:
-- ruby-head
-- 2.6.3
-- 2.5.5
+  - ruby-head
+  - 2.6.3
+  - 2.5.5
 branches:
   only: master
 before_install: bin/ci-install
 script:
-- RUBY_VERSION=$(ruby -e 'puts RUBY_VERSION') yarn test
-- yarn lint
-- yarn test
-- yarn print --check '**/*'
-- bundle exec rake test
+  - RUBY_VERSION=$(ruby -e 'puts RUBY_VERSION') yarn test
+  - yarn lint
+  - yarn test
+  - yarn print --check '**/*'
+  - bundle exec rake test
 cache:
-- bundler
-- yarn
+  - bundler
+  - yarn
 matrix:
   allow_failures:
     - rvm: ruby-head
diff --git a/CHANGELOG.md b/CHANGELOG.md
index de984032..34245307 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,17 +7,23 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 ## [Unreleased]
 
 ## [0.12.1] - 2019-04-22
+
 ### Changed
+
 - If a lambda literal is nested under a `command` or `command_call` node anywhere in the heirarchy, then it needs to use the higher-precedence `{ ... }` braces as opposed to the `do ... end` delimiters.
 - Calling `super` with a block and no args was causing the parser to fail when attempting to inspect lambda nodes. (Thanks to @jpickwell for the report.)
 - Support better breaking within interpolation by grouping the interpolated content.
 
 ## [0.12.0] - 2019-04-18
+
 ### Added
+
 - Automatically convert `lambda { ... }` method calls into `-> { ... }` literals.
 
 ## [0.11.0] - 2019-04-18
+
 ### Added
+
 - Support for parsing things with a ruby shebang (e.g., `#!/usr/bin/env ruby` or `#!/usr/bin/ruby`).
 - [INTERNAL] Big tests refactor.
 - Make multiple `when` predicates break at 80 chars and then wrap to be inline with the other predicates.
@@ -28,6 +34,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Support automatically transforming `def/begin/rescue/end/end` into `def/rescue/end`.
 
 ### Changed
+
 - Fixed support for dynamic string hash keys. (Thanks to @deecewan.)
 - [INTERNAL] Moved `case/when` into its own file and added better documentation.
 - [INTERNAL] Moved `begin/rescue` into its own file.
@@ -40,35 +47,46 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - [INTERNAL] Moved hashes into its own file.
 
 ## [0.10.0] - 2019-03-25
+
 ### Added
+
 - Support for block-local variables.
 - Support for dyna-symbols that are using single quotes.
 
 ### Changed
+
 - Force method calls after arrays, blocks, hashes, and xstrings to hang onto the end of the previous nodes.
 - Check before anything else for an invalid ruby version.
 
 ## [0.9.1] - 2019-03-24
+
 ### Changed
+
 - Better support string quotes by favoring what the user chose if the string contains escape patterns.
 - Better support heredocs within method calls.
 
 ## [0.9.0] - 2019-03-18
+
 ### Added
+
 - Support the `hasPragma` function.
 - Support the new `number_arg` node type in Ruby 2.7.
 
 ### Changed
+
 - Limit the number of nodes that are allowed to turn into ternary expressions.
 
 ## [0.8.0] - 2019-03-08
+
 ### Added
+
 - [INTERNAL] Add `eslint` and fix up existing violations.
 - Add the infra for the `prettier` ruby gem. (Thanks to @AlanFoster.)
 - Add a `rake` task for easier process integration for the ruby gem.
 - Handle direct interpolation of strings with %w array literals (i.e., `["#{foo}"]` should not be transformed into a %w array).
 
 ### Changed
+
 - Fix string escaping for hex digit bit patterns when there's only one character after the "x".
 - Don't allow line breaks between brace block params. (Thanks to @AlanFoster.)
 - [INTERNAL] Switch over the array.rb test case to minitest. (Thanks to @johnschoeman.)
@@ -79,10 +97,13 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Changed the ruby executable within the `prettier` gem to `rbprettier` for easier autocomplete.
 
 ### Removed
+
 - All instances of the spread (`...`) operator so that we can support older versions of node.
 
 ## [0.7.0] - 2019-02-24
+
 ### Changed
+
 - Support checking for escaping within strings to force double quotes (e.g., "\n").
 - Handle cases with empty class and module declarations that need to break. (Thanks to @RossKinsella for the report.)
 - [INTERNAL] Align the `bin/print` and `bin/sexp` API to support `bin/print` taking a filepath. (Thanks to @AlanFoster.)
@@ -101,14 +122,18 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Support multiple arguments to `undef`. (Thanks to @AlanFoster.)
 
 ## [0.6.3] - 2019-02-18
+
 ### Changed
+
 - [INTERNAL] Switch over `binary` fixture to minitest.
 - [INTERNAL] Reconfigure parser into multiple layer modules so that it's easier to understand and manage.
 - Handle comments from within `begin`, `rescue`, `ensure`, `while`, and `until` nodes.
 - Properly indent heredocs without taking into account current indentation level.
 
 ## [0.6.2] - 2019-02-17
+
 ### Changed
+
 - Handle regexp suffixes. (Thanks to @AlanFoster.)
 - [INTERNAL] Add support for testing the test fixtures with minitest.
 - [INTERNAL] Switch over `alias` and `regexp` tests to minitest.
@@ -116,12 +141,16 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Handle blocks args when trailing commas are on. (Thanks to @christoomey for the report.)
 
 ## [0.6.1] - 2019-02-15
+
 ### Changed
+
 - Fix Ruby 2.5 inline comments on `args_add_block` nodes. (Thanks to @meleyal for the report.)
 - Support passing `super()` explicitly with no arguments. (Thanks to @meleyal for the report.)
 
 ## [0.6.0] - 2019-02-14
+
 ### Added
+
 - Handle non UTF-8 comments.
 - Handle non UTF-8 identifiers.
 - Handle non UTF-8 strings.
@@ -129,58 +158,79 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Handle rescue with splats preceeding the exception names.
 
 ### Changed
+
 - Use `JSON::fast_generate` to get the s-expressions back from the parser.
 - Handle broken lambdas from within `command` and `command_call` nodes. (Thanks to @NoahTheDuke for the report.)
 
 ## [0.5.2] - 2019-02-13
+
 ### Changed
+
 - Support embedded expressions within strings that contain only keywords, as in `"#{super}"`.
 
 ## [0.5.1] - 2019-02-13
+
 ### Changed
+
 - Force `do` blocks that we know have to be `do` blocks to break. (Thanks to @yuki24 for the report.)
 - Handle `command` and `command_call` nodes `do` blocks by forcing them to break. (Thanks to @kmcq for the report.)
 - Attach comments to full hash association nodes, not just the value. (Thanks to @ashfurrow for the report.)
 
 ## [0.5.0] - 2019-02-13
+
 ### Added
+
 - Automatically convert arrays of all string literals to %w arrays.
 - Automatically convert arrays of all symbol literals to %i arrays.
 
 ### Changed
+
 - [INTERNAL] Move the `args_add` and `args_new` handling into the parser.
 - Change `command_call` nodes to properly indent when broken and to not add a trailing comma. (Thanks to @uri for the report.)
 - Rename the `trailingComma` option to `addTrailingCommas` to not conflict with the JS option.
 
 ## [0.4.1] - 2019-02-12
+
 ### Changed
+
 - [INTERNAL] Provide the `makeList` utility for the nodes that are lists from within ripper.
 - Again, this time for real, properly escape strings. (Thanks to @awinograd for the report.)
 - Fix up trailing commas on command calls.
 
 ## [0.4.0] - 2019-02-12
+
 ### Added
+
 - Support the `trailingComma` configuration option (defaults to `false`). (Thanks to @Overload119 for the request.)
 
 ### Changed
+
 - Pass the code to be formatted over `stdin`. (Thanks to @NoahTheDuke for the report.)
 
 ## [0.3.7] - 2019-02-11
+
 ### Changed
+
 - Split up statements even if they started on the same line with `;`s unless they are within an embedded expression.
 - Properly handle escaped quotes within strings.
 
 ## [0.3.6] - 2019-02-10
+
 ### Changed
+
 - Support the `not` operator properly. (Thanks to @AlanFoster for the report.)
 - Handle comments properly inside `if`, `unless`, and `when` nodes. (Thanks to @AlanFoster for the report.)
 
 ## [0.3.5] - 2019-02-09
+
 ### Changed
+
 - Handle lonely operators in Ruby `2.5`.
 
 ## [0.3.4] - 2019-02-09
+
 ### Changed
+
 - Comments are now properly attached inside `defs` nodes.
 - Support multiple inline comments on nodes.
 - Support inline comments from within the `EXPR_END|EXPR_LABEL` lexer state.
@@ -189,29 +239,38 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Handle `next` node edge case with `args_add` as the body. (Thanks to @eins78 for the report.)
 
 ## [0.3.3] - 2019-02-09
+
 ### Changed
+
 - Command nodes within conditionals now break parents to disallow them from being turned into ternary expressions. (Thanks to @bugthing for the report.)
 - Properly escape double quotes when using `preferSingleQuotes: false`. (Thanks to @awinograd for the report.)
 
 ## [0.3.2] - 2019-02-09
+
 ### Changed
+
 - [INTERNAL] Don't define duplicated methods in the parser.
 - Let prettier know about `.rb` and `.rake` files so you don't have to specify the parser when running.
 - Renamed the package to @prettier/plugin-ruby.
 
 ## [0.3.1] - 2019-02-07
+
 ### Changed
+
 - Automatically add parens to method declarations.
 - Handle comments on bare hash assocs.
 - Handle `method_add_block` nodes where the statements may be nested one more level.
 - Handle heredocs nested no matter how many levels deep.
 
 ## [0.3.0] - 2019-02-07
+
 ### Added
+
 - Support squiggly heredocs.
 - Support straight heredocs.
 
 ### Changed
+
 - Ignore current indentation when creating embdocs so that `=begin` is always at the beginning of the line.
 - [INTERNAL] Move `regexp_add` and `regexp_new` handling into the parser.
 - [INTERNAL] Move `xstring_add` and `xstring_new` handling into the parser.
@@ -220,17 +279,22 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - [INTERNAL] Move `mlhs_add` and `mlhs_new` handling into the parser.
 
 ## [0.2.1] - 2019-02-06
+
 ### Changed
+
 - Handle brace blocks on commands properly.
 - Break parent and return `do` blocks when called from a `command` node.
 - Handle edge cases with `if` statements where there is no body of the if (so it can't be converted to a ternary).
 
 ## [0.2.0] - 2019-02-06
+
 ### Added
+
 - Handle `methref` nodes from Ruby `2.7`.
 - Allow `module` nodes to shorten using `;` when the block is empty.
 
 ### Changed
+
 - Handle splat within an array, as in `[1, 2, *foo]`.
 - Disallow comments from being attached to intermediary regex nodes.
 - Fix `to_proc` transforms to reference the method called as opposed to the parameter name.
@@ -242,11 +306,15 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - [INTERNAL] Handle intermediary array nodes in the parse for better comment handling.
 
 ## [0.1.2] - 2019-02-05
+
 ### Changed
+
 - Handle guard clauses that return with no parens.
 
 ## [0.1.1] - 2019-02-05
+
 ### Changed
+
 - Handle class method calls with the `::` operator.
 - Handle strings with apostrophes when using `preferSingleQuote`.
 - [INTERAL] Have travis run multiple ruby versions.
@@ -254,10 +322,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Disallow comments from being attached to intermediary string nodes.
 
 ## [0.1.0] - 2019-02-04
+
 ### Added
+
 - Initial release 🎉
 
-[Unreleased]: https://github.com/prettier/plugin-ruby/compare/v0.12.1...HEAD
+[unreleased]: https://github.com/prettier/plugin-ruby/compare/v0.12.1...HEAD
 [0.12.1]: https://github.com/prettier/plugin-ruby/compare/v0.12.0...v0.12.1
 [0.12.0]: https://github.com/prettier/plugin-ruby/compare/v0.11.0...v0.12.0
 [0.11.0]: https://github.com/prettier/plugin-ruby/compare/v0.10.0...v0.11.0
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
index d7fd5f1b..06a97449 100644
--- a/CODE_OF_CONDUCT.md
+++ b/CODE_OF_CONDUCT.md
@@ -14,22 +14,22 @@ appearance, race, religion, or sexual identity and orientation.
 Examples of behavior that contributes to creating a positive environment
 include:
 
-* Using welcoming and inclusive language
-* Being respectful of differing viewpoints and experiences
-* Gracefully accepting constructive criticism
-* Focusing on what is best for the community
-* Showing empathy towards other community members
+- Using welcoming and inclusive language
+- Being respectful of differing viewpoints and experiences
+- Gracefully accepting constructive criticism
+- Focusing on what is best for the community
+- Showing empathy towards other community members
 
 Examples of unacceptable behavior by participants include:
 
-* The use of sexualized language or imagery and unwelcome sexual attention or
- advances
-* Trolling, insulting/derogatory comments, and personal or political attacks
-* Public or private harassment
-* Publishing others' private information, such as a physical or electronic
- address, without explicit permission
-* Other conduct which could reasonably be considered inappropriate in a
- professional setting
+- The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+- Trolling, insulting/derogatory comments, and personal or political attacks
+- Public or private harassment
+- Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+- Other conduct which could reasonably be considered inappropriate in a
+  professional setting
 
 ## Our Responsibilities
 
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index bc0b0222..b2496d16 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -14,6 +14,7 @@ Ripper is the built-in CRuby lexer and parser that understands your Ruby code. I
 
 You can explore Ripper within an interactive Ruby terminal. The process of identifying the tokens within your source code is called lexing:
 
+<!-- prettier-ignore -->
 ```ruby
 $ irb
 > require 'ripper'
@@ -24,6 +25,7 @@ $ irb
 
 Once the tokens are understood, Ripper constructs an abstract syntax tree:
 
+<!-- prettier-ignore -->
 ```ruby
 $ irb
 > require 'ripper'
diff --git a/README.md b/README.md
index 2252093e..6ed49ca3 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,7 @@ Under the hood `@prettier/plugin-ruby` uses Ruby's own `ripper` library which al
 
 For example, the below [code segment](http://www.rubyinside.com/advent2006/4-ruby-obfuscation.html):
 
+<!-- prettier-ignore -->
 ```ruby
         d=[30644250780,9003106878,
     30636278846,66641217692,4501790980,
@@ -48,16 +49,16 @@ when run through `@prettier/plugin-ruby` will generate:
 
 ```ruby
 d = [
-  30644250780,
-  9003106878,
-  30636278846,
-  66641217692,
-  4501790980,
+  30_644_250_780,
+  9_003_106_878,
+  30_636_278_846,
+  66_641_217_692,
+  4_501_790_980,
   671_24_603036,
   131_61973916,
   66_606629_920,
-  30642677916,
-  30643069058
+  30_642_677_916,
+  30_643_069_058
 ]
 a, s = [], $*[0]
 s.each_byte { |b| a << ('%036b' % d[b.chr.to_i]).scan(/\d{6}/) }
diff --git a/bin/print b/bin/print
index b7cbb645..90095fd7 100755
--- a/bin/print
+++ b/bin/print
@@ -5,6 +5,9 @@ const prettier = require("prettier");
 
 const code = fs.existsSync(process.argv[2])
   ? fs.readFileSync(process.argv[2], "utf-8")
-  : process.argv.slice(2).join(" ").replace(/\\n/g, "\n");
+  : process.argv
+      .slice(2)
+      .join(" ")
+      .replace(/\\n/g, "\n");
 
 console.log(prettier.format(code, { parser: "ruby", plugins: ["."] }));