The header files of a request or response.

Neither the key nor the value can contain '\r' or '\n'. See https://tools.ietf.org/html/rfc7230#section-3.2

Empty list of headers.

• since 0.5

get k headers looks for the header field with key k.

• parameter f

  if provided, will transform the value before it is returned.

set k v headers sets the key k to value v. It erases any previous entry for k

Remove the key from the headers, if present.

Is there a header with the given key?

Pretty print the headers.