Allow "echo in"

Signed-off-by: Oleg Bulatov <dmage@yandex-team.ru>
Define operators in hash

Signed-off-by: Oleg Bulatov <dmage@yandex-team.ru>
Fix "..." string parsing

Signed-off-by: Oleg Bulatov <dmage@yandex-team.ru>
Add more examples

Signed-off-by: Oleg Bulatov <dmage@yandex-team.ru>