Today Palo Alto Networks (PANW), the cybersecurity software firm, reported positive and strong free cash flow (FCF) and FCF margins for its fiscal quarter ending April 30. Moreover, given the company’s FCF margin guidance, the stock looks cheap. PANW stock is down 2.55% in midday trading on May 21 at $317.07 per share. However, PANW stock is still up 18% in the last month and a half from $268.58 where it closed on April 8. Strong Results for the QuarterIn short, the company reported strong results, both for revenue (+15% Y/Y) and its all-important free cash flow (FCF) number for the quarter (+…