Error an activate plugin

An get error to activate plugin

El plugin no ha podido activarse porque ha provocado un error fatal.

Parse error: syntax error, unexpected T_FUNCTION in /home/u54723/domains/erufenix.com.mx/public_html/wp-content/plugins/wp-markdown-syntaxhighlighter/wp-markdown-syntaxhighlighter.php on line 49

line 49 in wp-markdown-syntaxhighlighter.php

function wmsh_filter_markdown( $text ) {
	$return = preg_replace_callback(
		'<pre><code>#!!([^\n]+)\n(.*?)</code></pre>|s',
		function( $m ) {
			return wmsh_add_parameters($m[2], $m[1]);
		},
		$text
	);

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