<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def standalone(body):
 """ Returns complete html document given markdown html """

    with open(_ROOT + '/html.dat', 'r') as html_template:
        head = html_title()
        html = "".join(html_template.readlines()) \
                 .replace("{{HEAD}}", head) \
                 .replace("{{BODY}}", body)
        return html