Duplicate function definition, was: Dragging custom indicator onto chart twice causes error

Hi,
I am trying to create a custom indicator, this is just a sample below of the syntax I am using. But if I drag this code onto a chart twice, it causes an error

"..unexpected USER_FN, expecting identifier"

How can I resolve thanks?

procedure DoSomething(string)
{
	_TRACE(string);
}

DoSomething("Hello");

You are getting error because you have DUPLICATE function definition if you drag-drop file twice. Instead of placing function definition in the formula that you drag drop, place your functions inside include file (separate) and use #include_once