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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 namedb_name_update( cur, opcode, input_opdata, only_if={}, constraints_ignored=[] ):
 """ Update an existing name in the database. If non-empty, only update the given fields. DO NOT CALL THIS METHOD DIRECTLY. """


    opdata = copy.deepcopy( input_opdata )
    namedb_name_fields_check( opdata )
    mutate_fields = op_get_mutate_fields( opcode )

    if opcode not in OPCODE_CREATION_OPS:
        assert 'name' not in mutate_fields, "BUG: 'name' listed as a mutate field for '%s'" % (opcode)

    # reduce opdata down to the given fields....
    must_equal = namedb_update_must_equal( opdata, mutate_fields )
    must_equal += ['name','block_number']

    for ignored in constraints_ignored:
        if ignored in must_equal:
            # ignore this constraint 
            must_equal.remove( ignored )

    try:
        query, values = namedb_update_prepare( cur, ['name', 'block_number'], opdata, "name_records", must_equal=must_equal, only_if=only_if )
    except Exception, e:
        log.exception(e)
        log.error("FATAL: failed to update name '%s'" % opdata['name'])
        os.abort()

    namedb_query_execute( cur, query, values )

    try:
        assert cur.rowcount == 1, "Updated %s row(s)" % cur.rowcount 
    except Exception, e:
        log.exception(e)
        log.error("FATAL: failed to update name '%s'" % opdata['name'])
        log.error("Query: %s", "".join( ["%s %s" % (frag, "'%s'" % val if type(val) in [str, unicode] else val) for (frag, val) in zip(query.split("?"), values + ("",))] ))
        os.abort()

    return True