val fold :
init:'a->fixed_idx:('a->(Base.int ->axis_index)Variantslib.Variant.t->'b)->iterator:('b->(symbol->axis_index)Variantslib.Variant.t->'c)->'c
val iter :
fixed_idx:((Base.int ->axis_index)Variantslib.Variant.t->Base.unit)->iterator:((symbol->axis_index)Variantslib.Variant.t->Base.unit)->Base.unit