code: func HelperNameStr(node Node) (string, bool) {
  	// PathExpression
  	if str, ok := PathExpressionStr(node); ok {
  		return str, ok
  	}
  
  	// Literal
  	if str, ok := LiteralStr(node); ok {
  		return str, ok
  	}
  
  	return "", false
  }
docs: // HelperNameStr returns the string representation of a helper name, with a boolean set to false if this is not a valid helper name.
  //
  // helperName : path | dataName | STRING | NUMBER | BOOLEAN | UNDEFINED | NULL