Definir string de agente do usuário phantomjs

Definir o agente do usuário para o driver phantomjs

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

dcap
= dict(DesiredCapabilities.PHANTOMJS)
dcap
["phantomjs.page.settings.userAgent"] = (
"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/53 "
"(KHTML, like Gecko) Chrome/15.0.87"
)
driver
= webdriver.PhantomJS(desired_capabilities=dcap)