Function SCIPmultihashInsert 

pub unsafe extern "C" fn SCIPmultihashInsert(
    multihash: *mut SCIP_MULTIHASH,
    element: *mut c_void,
) -> SCIP_RETCODE

inserts element in multihash table (multiple inserts of same element possible)

@note A pointer to a multihashlist returned by SCIPmultihashRetrieveNext() might get invalid when adding an element to the hash table, due to dynamic resizing.