'Check validity of a credentials file.'

def _validate_creds_file(self, verbose=False):

    oauth1 = False
    oauth1_keys = ['app_key', 'app_secret', 'oauth_token', 'oauth_token_secret']
    oauth2 = False
    oauth2_keys = ['app_key', 'app_secret', 'access_token']
    if all(((k in self.oauth) for k in oauth1_keys)):
        oauth1 = True
    elif all(((k in self.oauth) for k in oauth2_keys)):
        oauth2 = True
    if (not (oauth1 or oauth2)):
        msg = 'Missing    or    incorrect    entries    in    {}\n'.format(self.creds_file)
        msg += pprint.pformat(self.oauth)
        raise ValueError(msg)
    elif verbose:
        print('Credentials    file    "{}"    looks    good'.format(self.creds_file))
