set_flags_from_environment

# File railties/guides/rails_guides/generator.rb, line 87
    def set_flags_from_environment
      @edge     = ENV['EDGE']     == '1'
      @warnings = ENV['WARNINGS'] == '1'
      @all      = ENV['ALL']      == '1'
      @kindle   = ENV['KINDLE']   == '1'
      @version  = ENV['RAILS_VERSION'] || `git rev-parse --short HEAD`.chomp
      @lang     = ENV['GUIDES_LANGUAGE']
    end