
This special lexer mode has several use cases:

Long command lines without trailing \

    % chromium-browser
      --no-proxy-server
      # comments allowed
      --incognito

Long pipelines or and-or chains without trailing \ 

    % find .
    # exclude tests
    | grep -v '_test.py'
    | xargs wc -l
    | sort -n

    %  ls /
    && ls /bin
    && ls /lib
    || error "oops"

Using {} for brace expansion, rather than the start of a block:

    % echo {alice,bob}@example.com
    %
    echo next   # blank line or bare % required to end the command

NOTE: This should be valid without % :

    ls *.[ch]

Using Oil syntax at an OSH shell prompt:

    $   echo hi >&2    # POSIX sh syntax
    $ % echo hi > !2   # Oil syntax

