bind variables and dynamic ref cursors

I am writing stored procedures that return ref cursors to developers. For one query they have the option to send me 2 or 3 parameters. So this means I need 2 or 3 where clauses. using a dynamic ref cursor, how do i use 2 or 3 bind variables since the number of where cols = statements will vary?

I know how to use dynamic sql. I am not sure how to get this to work with ref cursors where the number of bind variables vary ?

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