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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_base_url(webdriver):
 """ Get the current base URL. Args: webdriver: Selenium WebDriver instance. Returns: str - base URL. Usage:: driver.get("http://www.google.com/?q=hello+world") WebUtils.get_base_url(driver) #returns 'http://www.google.com' """

        current_url = webdriver.current_url
        try:
            return re.findall("^[^/]+//[^/$]+", current_url)[0]
        except:
            raise RuntimeError(
                u("Unable to process base url: {0}").format(current_url))