def _get_login_info(self, username_option='username', password_option='password', netrc_machine=None):
"""
Get the login info as (username, password)
- It will look in the netrc file using the _NETRC_MACHINE value
+ First look for the manually specified credentials using username_option
+ and password_option as keys in params dictionary. If no such credentials
+ available look in the netrc file using the netrc_machine or _NETRC_MACHINE
+ value.
If there's no info available, return (None, None)
"""
if self._downloader is None: