A netrc instance has the following methods:
(login, account, password)
of authenticators for host.  If the netrc file did not
contain an entry for the given host, return the tuple associated with
the `default' entry.  If neither matching host nor default entry is
available, return None.
Instances of netrc have public instance variables:
(login, account,
password) tuples.  The `default' entry, if any, is represented
as a pseudo-host by that name.