type tType t represents an incomplete header parse. Keep calling input on it until you
get a map from header name to column number.
val create : ?strip:bool ‑> ?sep:char ‑> ?quote:[ `No_quoting | `Using of char ] ‑> ?header:Header.t ‑> _ Builder.t ‑> (t, int Core.String.Map.t) Core.Either.tval input : t ‑> len:int ‑> string ‑> (t, int Core.String.Map.t * string) Core.Either.tinput t ~len s reads the first len bytes from s and returns either t or
header_map, unused_input.
val is_at_beginning_of_row : t ‑> bool