Return the next response header field name and value.
- A string that will contain the name of the first header field
returned by the server.
- A string that will contain the value of the specified header
This method returns a Boolean value. If the method succeeds,
it will return True. If the method fails, it will return False.
The GetNextHeader method is used get the next header field
name and value from the response header returned by the server. This
method should only be called after the client has requested the
resource. This method is used in conjunction with the
GetFirstHeader method to enumerate all of the response header
fields returned by the server.