def proxy_bypass_environment(host):
    """Test if proxies should not be used for a particular host.

    Checks the environment for a variable named no_proxy, which should
    be a list of DNS suffixes separated by commas, or '*' for all hosts.
    """
    no_proxy = os.environ.get('no_proxy', '') or os.environ.get('NO_PROXY', '')
    # '*' is special case for always bypass
    if no_proxy == '*':
        return 1
    # strip port off host
    hostonly, port = splitport(host)
    # check if the host ends with any of the DNS suffixes
    no_proxy_list = [proxy.strip() for proxy in no_proxy.split(',')]
    for name in no_proxy_list:
        if name and (hostonly.endswith(name) or host.endswith(name)):
            return 1
    # otherwise, don't bypass
    return 0
dataset/ETHPy150Open kleientertainment/ds_mod_tools/pkg/win32/Python27/Lib/urllib.py/proxy_bypass_environment/original