from typing import Sequence


def format_list(  # pylint: disable=R0913
    items: Sequence[str],
    header: str,
    indent=2,
    bullet_char="-",
    header_sep="=",
    prefix: str = "",
    suffix: str = "",
) -> str:
    """
    Format and return a string with the corresponding header and all the items each occupying a
    single line and with the specified indentation.
    """
    s = f"{header}: "
    if not items:
        s += " None."
        return s

    s += "\n" + len(s) * header_sep
    s += "\n\n"
    s += "\n".join(f'{" " * indent}{bullet_char} {item}' for item in items)
    s += "\n\n"
    return f"{prefix}{s}{suffix}"