def document_form_thumbnail_path(instance, filename):
    title = instance.title
    fn, ext = os.path.splitext(filename)
    datetime = datetime.now()
    re_filename = datetime.strftime('%Y%m%d_%H%M%S_') + title + 'thumbnail' + ext
    paths = ['document', 'document-form', re_filename]
    return os.path.join(paths)

def print_hi(name)
  puts "Hi, #{name}"
end
print_hi('Tom')
#=> prints 'Hi, Tom' to STDOUT.