add hdrs key value adds a
key and a
value to an existing
val get : t -> string -> string option
get hdrs key retrieves a
key from the given
hdrs headers. If the header is one of the set of headers defined to have list values, then all of the values are concatenated into a single string separated by commas and returned. If it is a singleton header, then the first value is returned and no concatenation is performed.
val init_with : string -> string -> t
init_with key value constructs a fresh map of HTTP headers with a single key and value entry.
val to_string : t -> string