module Markdown
  module Fixer

    def self.fix(markdown, pattern=@fix_all_pattern)
      pattern.map do |key, value|
        markdown.gsub!(key.to_s, value.to_s)
      end
      markdown
    end

    @fix_all_pattern = {
      'title': '"title"',
      'hr': 'hhr',
      '\r\n': '\n',
      'tags': 't a g s'
    }
  end
end

# Usage:
# returns: "title" hhr t a g s\n
Markdown::Fixer.fix('title hr tags\r\n')

# Provide a custom pattern:
# returns: title hr tags\n
Markdown::Fixer.fix('title hr tags\r\n', {'\r\n': '\n'})