human
Complete the below
def canonicalize_cfg_single_backedge(blocks):

    ''''Rewrite loops that have multiple backedges.'
    '''
 ... Write me a the Python program you requested?
assistant
#Here is the Python program you requested.
    cfg = compute_cfg_from_blocks(blocks)
    newblocks = blocks.copy()
    def new_block_id():
        return (max(newblocks.keys()) + 1)
    def has_multiple_backedges(loop):
        count = 0
        for k in loop.body:
            blk = blocks[k]
            edges = blk.terminator.get_targets()
            if (loop.header in edges):
                count += 1
                if (count > 1):
                    return True
        return False
    def yield_loops_with_multiple_backedges():
        for lp in cfg.loops().values():
            if has_multiple_backedges(lp):
                (yield lp)
    def replace_target(term, src, dst):
        def replace(target):
            return (dst if (target == src) else target)
        if isinstance(term, ir.Branch):
            return ir.Branch(cond=term.cond, truebr=replace(term.truebr), falsebr=replace(term.falsebr), loc=term.loc)
        elif isinstance(term, ir.Jump):
            return ir.Jump(target=replace(term.target), loc=term.loc)
        else:
            assert (not term.get_targets())
            return term
    def rewrite_single_backedge(loop):
        '\n                                Add    new    tail    block    that    gathers    all    the    backedges\n                                '
        header = loop.header
        tailkey = new_block_id()
        for blkkey in loop.body:
            blk = newblocks[blkkey]
            if (header in blk.terminator.get_targets()):
                newblk = blk.copy()
                newblk.body[(-1)] = replace_target(blk.terminator, header, tailkey)
                newblocks[blkkey] = newblk
        entryblk = newblocks[header]
        tailblk = ir.Block(scope=entryblk.scope, loc=entryblk.loc)
        tailblk.append(ir.Jump(target=header, loc=tailblk.loc))
        newblocks[tailkey] = tailblk
    for loop in yield_loops_with_multiple_backedges():
        rewrite_single_backedge(loop)
    return newblocks