@noelrappin
In Programming Ruby 1.9, 2010 edition, this hash in page 21 was nicely aligned ;

inst_section = {
'cello'      => 'string',
'clarinet'   => 'woodwind',
'drum'       => 'percussion',
'oboe'       => 'woodwind',
'trumpet'    => 'brass',
'violin'     => 'string'
}

It’s just that I find that aligned identical things are more readable.

Same on pages 24-25 (page 23 of the 2010 book).

Regexp examples on page 27 : first line is not aligned, but could be :

/\d\d:\d\d:\d\d/     # a time such as 12:34:56
/Ruby.*Rust/       # Ruby, zero or more other chars, then Rust
/Ruby Rust/        # Ruby, exactly one space, and Rust
...
/Java (Ruby|Rust)/ # Java, a space, and either Ruby or Rust

Start of page 28 could be :

line = gets
newline = line.sub(/Python/, 'Ruby')    # replace first 'Python' with 'Ruby'
newerline = line.gsub(/Python/, 'Ruby') # replace every 'Python' with 'Ruby'

Bottom of page 29 :

animals = ["ant", "bee", "cat", "dog"]    # create an array    <<<<========
animals.each { |animal| puts animal }   # iterate over the contents

By the way thank you for spending a lot of time writing this book. As I am back to Ruby, I’m glad to have an updated version. My latest book is 12 years old and I prefer reading a book than constantly searching the Internet.