explaing get_the_author

function get_the_author($deprecated = '') {
global $authordata;

if ( !empty( $deprecated ) )
_deprecated_argument( __FUNCTION__, '2.1' );

return apply_filters('the_author', is_object($authordata) ? $authordata->display_name : null);
}

can any one explain this function how it works and what is the meaning of _deprecated_argument(__FUNCTION__, '2.1' ); here


Thanks in advance

 

the answer:

http://codex.wordpress.org/Function_Reference/get_the_author