The following blocks of code search through the list 'numbers' for the value entered into the 'numberinput' textbox. What value should be used in the missing block for this code to work correctly?

initialize app variable index to $0$

when submitButton $*$ Click $*$

do set app variable index $*$ to in list app variable numbers $>$ find first $*$ occurrence of item $($numberInput $*\text{'}$s Text $*$

else set outputlabel $=\text{'}$s Text grad to $6$ join "Value found at index: $")$

$2$

$0$

$10$

$3$

$30$

False

$20$

True

$1$