def is_copy_consistent(filename, overwrite=False):
    """
    Check if the code commented as a copy in `filename` matches the original.
    Return the differences or overwrites the content depending on `overwrite`.
    """
    with open(filename, "r", encoding="utf-8", newline="\n") as f:
        lines = f.readlines()
    diffs = []
    line_index = 0
    # Not a for loop cause `lines` is going to change (if `overwrite=True`).
    while line_index < len(lines):
        search = _re_copy_warning.search(lines[line_index])
        if search is None:
            line_index += 1
            continue

        # There is some copied code here, let's retrieve the original.
        indent, object_name, replace_pattern = search.groups()
        theoretical_code = find_code_in_diffusers(object_name)
        theoretical_indent = get_indent(theoretical_code)

        start_index = line_index + 1 if indent == theoretical_indent else line_index + 2
        indent = theoretical_indent
        line_index = start_index

        # Loop to check the observed code, stop when indentation diminishes or if we see a End copy comment.
        should_continue = True
        while line_index < len(lines) and should_continue:
            line_index += 1
            if line_index >= len(lines):
                break
            line = lines[line_index]
            should_continue = _should_continue(line, indent) and re.search(f"^{indent}# End copy", line) is None
        # Clean up empty lines at the end (if any).
        while len(lines[line_index - 1]) <= 1:
            line_index -= 1

        observed_code_lines = lines[start_index:line_index]
        observed_code = "".join(observed_code_lines)

        # Before comparing, use the `replace_pattern` on the original code.
        if len(replace_pattern) > 0:
            patterns = replace_pattern.replace("with", "").split(",")
            patterns = [_re_replace_pattern.search(p) for p in patterns]
            for pattern in patterns:
                if pattern is None:
                    continue
                obj1, obj2, option = pattern.groups()
                theoretical_code = re.sub(obj1, obj2, theoretical_code)
                if option.strip() == "all-casing":
                    theoretical_code = re.sub(obj1.lower(), obj2.lower(), theoretical_code)
                    theoretical_code = re.sub(obj1.upper(), obj2.upper(), theoretical_code)

            # Blackify after replacement. To be able to do that, we need the header (class or function definition)
            # from the previous line
            theoretical_code = blackify(lines[start_index - 1] + theoretical_code)
            theoretical_code = theoretical_code[len(lines[start_index - 1]) :]

        # Test for a diff and act accordingly.
        if observed_code != theoretical_code:
            diffs.append([object_name, start_index])
            if overwrite:
                lines = lines[:start_index] + [theoretical_code] + lines[line_index:]
                line_index = start_index + 1

    if overwrite and len(diffs) > 0:
        # Warn the user a file has been modified.
        print(f"Detected changes, rewriting {filename}.")
        with open(filename, "w", encoding="utf-8", newline="\n") as f:
            f.writelines(lines)
    return diffs

    Check if the code commented as a copy in `filename` matches the original.
    Return the differences or overwrites the content depending on `overwrite`.
    
promptist/diffusers/utils/check_copies.py