hello world

require 'csv'

class A < B; def self.create(object = User) object end end
class Zebra; def inspect; "X#{2 + self.object_id}" end end

module ABC::DEF
  include Comparable

  # @param test
  # @return [String] nothing
  def foo(test)
    Thread.new do |blockvar|
      ABC::DEF.reverse(:a_symbol, :'a symbol', :<=>, 'test' + test)
    end.join
  end

  def [](index) self[index] end
  def ==(other) other == self end
end

anIdentifier = an_identifier
Constant = 1
render action: :new
ARCTORIC = 'blah'

class CsvReader
  def initialize
    @books_in_stock = []
  end
  
  def read_in_csv_data(csv_file_name)
    CSV.foreach(csv_file_name, headers: true) do |row|
      @books_in_stock << BookInStock.new(row["ISBN"], row["Amount"])
    end
  end
  
  def total_value_in_stock
    sum = 0.0
    @books_in_stock.each {|book| sum += book.price}
    sum
  end
  
  def number_of_each_isbn
    # ...
  end
end