from typing import List


def ip_addresses_from_xff(value: str) -> List[str]:
    """
    Returns a list of IP addresses (as strings), given the value of an HTTP
    ``X-Forwarded-For`` (or ``WSGI HTTP_X_FORWARDED_FOR``) header.

    Args:
        value:
            the value of an HTTP ``X-Forwarded-For`` (or ``WSGI
            HTTP_X_FORWARDED_FOR``) header

    Returns:
        a list of IP address as strings

    See:
    - https://en.wikipedia.org/wiki/X-Forwarded-For
    - https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For  # noqa
    - NOT THIS: http://tools.ietf.org/html/rfc7239
    """
    if not value:
        return []
    return [x.strip() for x in value.split(",")]
    # ... separator is comma-space, but let's be liberal