Blockly:LISTS INDEX OF TOOLTIP/qqq
tooltip - %1 will be replaced by either the number 0 or -1 depending on the indexing mode. See https://github.com/google/blockly/wiki/Lists#finding-items-in-a-list. 
tooltip - %1 will be replaced by either the number 0 or -1 depending on the indexing mode. See https://github.com/google/blockly/wiki/Lists#finding-items-in-a-list.