Function SCIPexpriterSetCurrentUserData 

pub unsafe extern "C" fn SCIPexpriterSetCurrentUserData(
    iterator: *mut SCIP_EXPRITER,
    userdata: SCIP_EXPRITER_USERDATA,
)

sets the iterator specific user data of the current expression for an expression iteration if in DFS mode

@note The expression iterator mode must be DFS or another mode with allowrevisit=FALSE