How to use the bytecode.instr.Instr function in bytecode

if jump_target is None:
                instr = Instr(instr.name, arg, lineno=lineno)
            else:
                instr_index = len(instructions)
            instructions.append(instr)
            offset += size

            if jump_target is not None:
                jumps.append((instr_index, jump_target))

        # replace jump targets with labels
        for index, jump_target in jumps:
            instr = instructions[index]
            # FIXME: better error reporting on missing label
            label = labels[jump_target]
            instructions[index] = Instr(instr.name, label, lineno=instr.lineno)

        bytecode = _bytecode.Bytecode()
        bytecode._copy_attr_from(self)

        nargs = bytecode.argcount + bytecode.kwonlyargcount
        if sys.version_info > (3, 8):
            nargs += bytecode.posonlyargcount
        if bytecode.flags & inspect.CO_VARARGS:
            nargs += 1
        if bytecode.flags & inspect.CO_VARKEYWORDS:
            nargs += 1
        bytecode.argnames = self.varnames[:nargs]
        _set_docstring(bytecode, self.consts)

        bytecode.extend(instructions)
        return bytecode

def __call__(self, *args, **kwargs) -> Instr:
        ret = Instr(self.name, *args, **kwargs)
        self.instrs.append(ret)
        return ret

const_key,
    _check_arg_int,
)

_WORDCODE = sys.version_info >= (3, 6)


def _set_docstring(code, consts):
    if not consts:
        return
    first_const = consts[0]
    if isinstance(first_const, str) or first_const is None:
        code.docstring = first_const


class ConcreteInstr(Instr):
    """Concrete instruction.

    arg must be an integer in the range 0..2147483647.

    It has a read-only size attribute.
    """

    __slots__ = ("_size", "_extended_args")

    def __init__(self, name, arg=UNSET, *, lineno=None, extended_args=None):
        # Allow to remember a potentially meaningless EXTENDED_ARG emitted by
        # Python to properly compute the size and avoid messing up the jump
        # targets
        self._extended_args = extended_args
        self._set(name, arg, lineno)

ncells = len(self.bytecode.cellvars)
        lineno = self.bytecode.first_lineno

        for instr in self.bytecode:
            if isinstance(instr, Label):
                self.labels[instr] = len(self.instructions)
                continue

            if isinstance(instr, SetLineno):
                lineno = instr.lineno
                continue

            if isinstance(instr, ConcreteInstr):
                instr = instr.copy()
            else:
                assert isinstance(instr, Instr)

                if instr.lineno is not None:
                    lineno = instr.lineno

                arg = instr.arg
                is_jump = isinstance(arg, Label)
                if is_jump:
                    label = arg
                    # fake value, real value is set in compute_jumps()
                    arg = 0
                elif instr.opcode in _opcode.hasconst:
                    arg = self.add_const(arg)
                elif instr.opcode in _opcode.haslocal:
                    arg = self.add(self.varnames, arg)
                elif instr.opcode in _opcode.hasname:
                    arg = self.add(self.names, arg)

elif instr.opcode in _opcode.haslocal:
                arg = self.varnames[arg]
            elif instr.opcode in _opcode.hasname:
                arg = self.names[arg]
            elif instr.opcode in _opcode.hasfree:
                if arg < ncells:
                    name = self.cellvars[arg]
                    arg = CellVar(name)
                else:
                    name = self.freevars[arg - ncells]
                    arg = FreeVar(name)
            elif instr.opcode in _opcode.hascompare:
                arg = Compare(arg)

            if jump_target is None:
                instr = Instr(instr.name, arg, lineno=lineno)
            else:
                instr_index = len(instructions)
            instructions.append(instr)
            offset += size

            if jump_target is not None:
                jumps.append((instr_index, jump_target))

        # replace jump targets with labels
        for index, jump_target in jumps:
            instr = instructions[index]
            # FIXME: better error reporting on missing label
            label = labels[jump_target]
            instructions[index] = Instr(instr.name, label, lineno=instr.lineno)

        bytecode = _bytecode.Bytecode()

def from_bytecode(bytecode):
        # label => instruction index
        label_to_block_index = {}
        jumps = []
        block_starts = {}
        for index, instr in enumerate(bytecode):
            if isinstance(instr, Label):
                label_to_block_index[instr] = index
            else:
                if isinstance(instr, Instr) and isinstance(instr.arg, Label):
                    jumps.append((index, instr.arg))

        for target_index, target_label in jumps:
            target_index = label_to_block_index[target_label]
            block_starts[target_index] = target_label

        bytecode_blocks = _bytecode.ControlFlowGraph()
        bytecode_blocks._copy_attr_from(bytecode)
        bytecode_blocks.argnames = list(bytecode.argnames)

        # copy instructions, convert labels to block labels
        block = bytecode_blocks[0]
        labels = {}
        jumps = []
        for index, instr in enumerate(bytecode):
            if index in block_starts:

def _flat(self):
        instructions = []
        labels = {}
        jumps = []

        offset = 0
        for index, instr in enumerate(self):
            if isinstance(instr, Label):
                instructions.append("label_instr%s" % index)
                labels[instr] = offset
            else:
                if isinstance(instr, Instr) and isinstance(instr.arg, Label):
                    target_label = instr.arg
                    instr = _bytecode.ConcreteInstr(instr.name, 0, lineno=instr.lineno)
                    jumps.append((target_label, instr))
                instructions.append(instr)
                offset += 1

        for target_label, instr in jumps:
            instr.arg = labels[target_label]

        return instructions