Python StringList for @= line concatenation

stringlist.py

from collections.abc import Sequence
from typing import cast, Self

import attrs

@attrs.define
class StringList:
    _lines: list[str] = attrs.Factory(list)

    @property
    def lines(self) -> list[str]:
        return self._lines

    def __matmul__(self, other) -> Self:
        if isinstance(other, str):
            return type(self)(self._lines + [other])
        elif isinstance(other, Sequence):
            ol = cast(list[str], other)
            return type(self)(self._lines + ol)
        else:
            raise TypeError(
                f"Unsupported operand type for @: 'StringList' and '{type(other).__name__}'"
            )

    def __str__(self) -> str:
        return "\n".join(self._lines)


def generate_espresso(einf: dict[str, tuple[int, int]]) -> str:
    el = StringList()
    el @= ".i 32"
    el @= ".o 1"
    el @= ".ilb " + " ".join([f"I{i}" for i in reversed(range(32))])
    el @= ".olb V"
    for i, kv in enumerate(einf.items()):
        bmi, bpi = kv[1]
        bits = ""
        for j in reversed(range(32)):
            sb = 1 << j
            if bmi & sb:
                if bpi & sb:
                    bits += "1"
                else:
                    bits += "0"
            else:
                bits += "-"
        bits += " 1"
        el @= bits
    el @= ".e"
    el @= ""
    return str(el)