Selenium PhantomJS custom headers in Python

I want to add "custom headers" to Selenium PhantomJS in python. These are the headers I wanna add.

headers = { 'Accept':'*/*',
            'Accept-Encoding':'gzip, deflate, sdch',
            'Accept-Language':'en-US,en;q=0.8',
            'Cache-Control':'max-age=0',
            'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36'
          }

This is the code I am working with:

from selenium import webdriver

service_args = [
    '--proxy=127.0.0.1:9999',
    '--proxy-type=socks5',
    ]
driver = webdriver.PhantomJS(service_args=service_args)


driver.set_window_size(1120, 550)
driver.get("https://duckduckgo.com/")
driver.find_element_by_id('search_form_input_homepage').send_keys("realpython")
driver.find_element_by_id("search_button_homepage").click()
print driver.current_url
driver.quit()

How do I modify the code incorporating those custom headers ?

Please help.

Setup headers in next way:

from selenium import webdriver


headers = { 'Accept':'*/*',
    'Accept-Encoding':'gzip, deflate, sdch',
    'Accept-Language':'en-US,en;q=0.8',
    'Cache-Control':'max-age=0',
    'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36'
}

for key, value in enumerate(headers):
    capability_key = 'phantomjs.page.customHeaders.{}'.format(key)
    webdriver.DesiredCapabilities.PHANTOMJS[capability_key] = value

Then start work with your driver:

service_args = [
    '--proxy=127.0.0.1:9999',
    '--proxy-type=socks5',
]
driver = webdriver.PhantomJS(service_args=service_args)
# ...............