Add to Variable / AddtoVariable (internally is.workflow.actions.appendvariable)
description
summary
Appends this action’s input to the specified variable, creating the variable if it does not exist.
This allows you to make a variable hold multiple items.
output
The updated contents of the variable.
usage
AddtoVariable (v:variableName | variableName)
arguments
variable: Variable Input (Docs)
Placeholder: 
		Variable Name
		
Allows Variables: true
Accepts a string with the name of the named variable (v:) you want to set, or a named variable (v:) that you want to set.
source json (for developers)
{
	"ActionClass": "WFAppendVariableAction",
	"ActionKeywords": [
		"add"
	],
	"Category": "Scripting",
	"Description": {
		"DescriptionResult": "The updated contents of the variable.",
		"DescriptionSummary": "Appends this action's input to the specified variable, creating the variable if it does not exist.\n\nThis allows you to make a variable hold multiple items."
	},
	"IconName": "Variable.png",
	"Input": {
		"Multiple": true,
		"Required": true,
		"TypePassthrough": true,
		"Types": [
			"WFContentItem"
		]
	},
	"Name": "Add to Variable",
	"Output": {
		"Multiple": true,
		"OutputName": "Variable",
		"Types": [
			"WFContentItem"
		]
	},
	"Parameters": [
		{
			"Class": "WFVariableFieldParameter",
			"Key": "WFVariableName",
			"Label": "Variable",
			"Placeholder": "Variable Name",
			"TextAlignment": "Right"
		}
	],
	"Subcategory": "Variables"
}