<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def find_element_by_css_selector(self, css_selector):
 """ Finds an element by css selector. :Args: - css_selector - CSS selector string, ex: 'a.nav#home' :Returns: - WebElement - the element if it was found :Raises: - NoSuchElementException - if the element wasn't found :Usage: :: element = driver.find_element_by_css_selector('#foo') """

        return self.find_element(by=By.CSS_SELECTOR, value=css_selector)