def _find_player_id(self, row):
player_id = row('<STR_LIT>').attr('<STR_LIT>')<EOL>if not player_id:<EOL><INDENT>player_id = row('<STR_LIT>').attr('<STR_LIT>')<EOL><DEDENT>return player_id<EOL>
Find the player's ID.

Find the player's ID as embedded in the 'data-append-csv' attribute,
such as 'zettehe01' for Henrik Zetterberg.

Parameters
----------
row : PyQuery object
    A PyQuery object representing a single row in a boxscore table for
    a single player.

Returns
-------
str
    Returns a ``string`` of the player's ID, such as 'zettehe01' for
    Henrik Zetterberg.