history length = 1
! echo ${two:-}
history length = 1
.! echo 'hi#'${two:-}
history length = 1
Couldn't parse historical command '(': Unexpected EOF while parsing command
history length = 1
Couldn't parse historical command 'a( )': Unexpected word while parsing compound command (Id.Eof_Real)
.history length = 1
! echo -l
history length = 1
! echo xx
history length = 1
.! echo yy
history length = 2
! echo "${five@P}"
history length = 2
! echo $three
history length = 2
.! echo -n $three ${4:-} "${five@P}"
history length = 3
! echo ${two:-}

history length = 3
! echo ${two:-} 
history length = 3
! echo 1
history length = 3
! ls /echo/
history length = 3
! echo ${two:-}
history length = 3
history length = 3
history length = 3
! ls /echo/
history length = 3
.
----------------------------------------------------------------------
Ran 5 tests in 0.003s

OK
! echo /echo/