'Creates a AsyncHTTPClient.
Only a single AsyncHTTPClient instance exists per IOLoop
in order to provide limitations on the number of pending connections.
``force_instance=True`` may be used to suppress this behavior.
Note that because of this implicit reuse, unless ``force_instance``
is used, only the first call to the constructor actually uses
its arguments. It is recommended to use the ``configure`` method
instead of the constructor to ensure that arguments take effect.
``max_clients`` is the number of concurrent requests that can be
in progress; when this limit is reached additional requests will be
queued. Note that time spent waiting in this queue still counts
against the ``request_timeout``.
``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
It can be used to make local DNS changes when modifying system-wide
settings like ``/etc/hosts`` is not possible or desirable (e.g. in
unittests).
``max_buffer_size`` (default 100MB) is the number of bytes
that can be read into memory at once. ``max_body_size``
(defaults to ``max_buffer_size``) is the largest response body
that the client will accept.  Without a
``streaming_callback``, the smaller of these two limits
applies; with a ``streaming_callback`` only ``max_body_size``
does.
.. versionchanged:: 4.2
Added the ``max_body_size`` argument.'

def initialize(self, max_clients=10, hostname_mapping=None, max_buffer_size=104857600, resolver=None, defaults=None, max_header_size=None, max_body_size=None):

    super(SimpleAsyncHTTPClient, self).initialize(defaults=defaults)
    self.max_clients = max_clients
    self.queue = collections.deque()
    self.active = {}
    self.waiting = {}
    self.max_buffer_size = max_buffer_size
    self.max_header_size = max_header_size
    self.max_body_size = max_body_size
    if resolver:
        self.resolver = resolver
        self.own_resolver = False
    else:
        self.resolver = Resolver()
        self.own_resolver = True
    if (hostname_mapping is not None):
        self.resolver = OverrideResolver(resolver=self.resolver, mapping=hostname_mapping)
    self.tcp_client = TCPClient(resolver=self.resolver)
