strip_heredoc.rb

# https://github.com/rails/rails/blob/e20dd73df42d63b206d221e2258cc6dc7b1e6068/activesupport/lib/active_support/core_ext/object/try.rb

class Object
  def try(*a, &b)
    if a.empty? && block_given?
      yield self
    else
      public_send(*a, &b) if respond_to?(a.first)
    end
  end
end

class NilClass
  def try(*args)
    nil
  end
end

# https://github.com/rails/rails/blob/e20dd73df42d63b206d221e2258cc6dc7b1e6068/activesupport/lib/active_support/core_ext/string/strip.rb

class String
  def strip_heredoc
    indent = scan(/^[ \t]*(?=\S)/).min.try(:size) || 0
    gsub(/^[ \t]{#{indent}}/, '')
  end
end

puts <<-CHARS
        A
         B
          C
           D
     CHARS
#        A
#         B
#          C
#           D

puts <<-CHARS.strip_heredoc
        E
         F
          G
           H
     CHARS
#E
# F
#  G
#   H