The workspace on which to create the variable.
Optionalopt_callback: (_0: string) => anyA callback. It will be passed an acceptable new variable name, or null if change is to be aborted (cancel button), or undefined if an existing variable was chosen.
Optionalopt_type: stringThe type of the variable like 'int', 'string', or ''. This will default to '', which is a specific type.
Original name of Blockly.Variables.createVariableButtonHandler(..).