def freeze(h, output_yaml, resolve, groups):
    """Output installed packages."""
    if not groups:
        groups = filter(lambda group: not group.lower().startswith("bower"),
                        h.requirements.keys())
    else:
        groups = [text_type.strip(group) for group in groups.split(",")]

    if output_yaml:
        for requirements in h.requirements.values():
            for requirement in requirements:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
        click.echo(h.requirements.yaml)
    else:
        for group in groups:
            if not h.requirements[group]:
                continue
            click.echo("# {}".format(group))
            for requirement in h.requirements[group]:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
                click.echo(str(requirement))
async def echo_client_streams(reader, writer):
    sock = writer.get_extra_info('socket')
    try:
        sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
    except (OSError, NameError):
        pass
    if PRINT:
        print('Connection from', sock.getpeername())
    while True:
        data = await reader.read(1000000)
        if not data:
            break
        writer.write(data)
    if PRINT:
        print('Connection closed')
    writer.close()