Retrieves dependencies for the given install requirement from the wheel cache.

    :param ireq: A single InstallRequirement
    :type ireq: :class:`~pip._internal.req.req_install.InstallRequirement`
    :return: A set of dependency lines for generating new InstallRequirements.
    :rtype: set(str) or None

def get_dependencies_from_wheel_cache(ireq):
    """Retrieves dependencies for the given install requirement from the wheel cache.

    :param ireq: A single InstallRequirement
    :type ireq: :class:`~pip._internal.req.req_install.InstallRequirement`
    :return: A set of dependency lines for generating new InstallRequirements.
    :rtype: set(str) or None
    """

    if ireq.editable or not is_pinned_requirement(ireq):
        return
    matches = WHEEL_CACHE.get(ireq.link, name_from_req(ireq.req))
    if matches:
        matches = set(matches)
        if not DEPENDENCY_CACHE.get(ireq):
            DEPENDENCY_CACHE[ireq] = [format_requirement(m) for m in matches]
        return matches
    return