code: func (v *evalVisitor) VisitMustache(node *ast.MustacheStatement) interface{} {
  	v.at(node)
  
  	// evaluate expression
  	expr := node.Expression.Accept(v)
  
  	// check if this is a safe string
  	isSafe := isSafeString(expr)
  
  	// get string value
  	str := Str(expr)
  	if !isSafe && !node.Unescaped {
  		// escape html
  		str = Escape(str)
  	}
  
  	return str
  }
docs: // VisitMustache implements corresponding Visitor interface method