Function SCIPexpriterGetChildIdxDFS 

pub unsafe extern "C" fn SCIPexpriterGetChildIdxDFS(
    iterator: *mut SCIP_EXPRITER,
) -> c_int

gets the index of the child that the expression iterator considers when in DFS mode and stage \ref SCIP_EXPRITER_VISITINGCHILD or \ref SCIP_EXPRITER_VISITEDCHILD