How to use the geventhttpclient.header.Headers function in geventhttpclient

    def __init__(self, method='GET', headers_type=Headers):
        super(HTTPResponse, self).__init__()
        self.method = method.upper()
        self.headers_complete = False
        self.message_begun = False
        self.message_complete = False
        self._headers_index = headers_type()
        self._header_state = HEADER_STATE_INIT
        self._current_header_field = None
        self._current_header_value = None
        self._header_position = 1
        self._body_buffer = bytearray()
        self.status_message = None

def __init__(self, host, port=None, headers=None,
                 block_size=BLOCK_SIZE,
                 connection_timeout=ConnectionPool.DEFAULT_CONNECTION_TIMEOUT,
                 network_timeout=ConnectionPool.DEFAULT_NETWORK_TIMEOUT,
                 disable_ipv6=False,
                 concurrency=1,
                 ssl=False, ssl_options=None, ssl_context_factory=None,
                 insecure=False,
                 proxy_host=None, proxy_port=None, version=HTTP_11,
                 headers_type=Headers):
        if headers is None:
            headers = {}
        self.host = host
        self.port = port
        connection_host = self.host
        connection_port = self.port
        if proxy_host is not None:
            assert proxy_port is not None, \
                'you have to provide proxy_port if you set proxy_host'
            self.use_proxy = True
            connection_host = proxy_host
            connection_port = proxy_port
        else:
            self.use_proxy = False
        if ssl and ssl_options is None:
            ssl_options = {}

try:
        return len(body)
    except TypeError:
        try:
            return os.fstat(body.fileno()).st_size
        except (AttributeError, OSError):
            return None


class HTTPClient(object):
    HTTP_11 = 'HTTP/1.1'
    HTTP_10 = 'HTTP/1.0'

    BLOCK_SIZE = 1024 * 4  # 4KB

    DEFAULT_HEADERS = Headers({
        'User-Agent': 'python/gevent-http-client-' + __version__
    })

    @classmethod
    def from_url(cls, url, **kw):
        if not isinstance(url, URL):
            url = URL(url)
        enable_ssl = url.scheme == PROTO_HTTPS
        if not enable_ssl:
            kw.pop('ssl_options', None)
        return cls(url.host, port=url.port, ssl=enable_ssl, **kw)

    def __init__(self, host, port=None, headers=None,
                 block_size=BLOCK_SIZE,
                 connection_timeout=ConnectionPool.DEFAULT_CONNECTION_TIMEOUT,
                 network_timeout=ConnectionPool.DEFAULT_NETWORK_TIMEOUT,

import six
if six.PY3:
    httplib = __import__('http.client').client
else:
    httplib = __import__('httplib')
from geventhttpclient import response
from geventhttpclient import header
import gevent.socket



class HTTPLibHeaders(header.Headers):

    def __getitem__(self, key):
        value = super(HTTPLibHeaders, self).__getitem__(key)
        if isinstance(value, (list, tuple)):
            return ", ".join(value)
        else:
            return value


class HTTPResponse(response.HTTPSocketResponse):

    def __init__(self, sock, method='GET', strict=0, debuglevel=0,
            buffering=False, **kw):
        if method is None:
            method = 'GET'
        else: