import difflib


def create_patch(filename: str, modified: str):
    """Create a unified diff between original and modified"""

    with open(filename, "r") as f:
        original = f.read()

    patch = "\n".join(
        difflib.unified_diff(
            original.splitlines(),
            modified.splitlines(),
            fromfile=filename,
            tofile=filename,
            lineterm="",
        )
    )

    return patch