Connect to Google Docs spreadsheet and return the first worksheet.

def login_open_sheet(oauth_key_file, spreadsheet):
    """Connect to Google Docs spreadsheet and return the first worksheet."""
    try:
        scope =  ['https://spreadsheets.google.com/feeds']
        credentials = ServiceAccountCredentials.from_json_keyfile_name(oauth_key_file, scope)
        gc = gspread.authorize(credentials)
        worksheet = gc.open(spreadsheet).sheet1
        return worksheet
    except Exception as ex:
        print('Unable to login and get spreadsheet.  Check OAuth credentials, spreadsheet name, and make sure spreadsheet is shared to the client_email address in the OAuth .json file!')
        print('Google sheet login failed with error:', ex)
        sys.exit(1)