Read text file line by line in python on-demand

readlines.py

from os import PathLike
from typing import Iterator

def readlines(filename: PathLike) -> Iterator[str]:
    """Reads a file line by line, yielding the lines as strings.

    Unlike Python's file object readlines method, this function does not read the entire file into
    memory, but reads it on demand.

    Args:
        filename: Path to the file to be read

    Returns:
        Iterator yielding each line of the file as a string with trailing whitespace removed
    """
    with open(filename, "rt") as f:
        for line in f:
            yield line.rstrip()