Source

File: wp-includes/pomo/po.php

public static function trim_quotes( $s ) {
			if ( '"' === substr( $s, 0, 1 ) ) {
				$s = substr( $s, 1 );
			}
			if ( '"' === substr( $s, -1, 1 ) ) {
				$s = substr( $s, 0, -1 );
			}
			return $s;
		}