Return a list of installed Distribution objects.
    ``skip`` argument is an iterable of lower-case project names to
    ignore; defaults to stdlib_pkgs

def get_installed_distributions(skip=stdlib_pkgs):
    """
    Return a list of installed Distribution objects.
    ``skip`` argument is an iterable of lower-case project names to
    ignore; defaults to stdlib_pkgs

    """
    return [d for d in pkg_resources.working_set
            if d.key not in skip]