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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def login(self, username, *, token=None):
 		"""Log in to Google Music. 		Parameters: 			username (str, Optional):
 Your Google Music username. 				Used for keeping stored OAuth tokens for multiple accounts separate. 			device_id (str, Optional):
 A mobile device ID or music manager uploader ID. 				Default: MAC address is used. 			token (dict, Optional):
 An OAuth token compatible with ``requests-oauthlib``. 		Returns: 			bool: ``True`` if successfully authenticated, ``False`` if not. 		"""


		self._username = username
		self._oauth(username, token=token)

		return self.is_authenticated