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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def format_hep(citation_elements):
 """Format hep-th report numbers with a dash e.g. replaces hep-th-9711200 with hep-th/9711200 """

    prefixes = ('astro-ph-', 'hep-th-', 'hep-ph-', 'hep-ex-', 'hep-lat-',
                'math-ph-')
    for el in citation_elements:
        if el['type'] == 'REPORTNUMBER':
            for p in prefixes:
                if el['report_num'].startswith(p):
                    el['report_num'] = el['report_num'][:len(p) - 1] + '/' + \
                        el['report_num'][len(p):]
    return citation_elements