Indicatore Forex Trading Sessions

//@version=3
study(title="Indicatore Forex trading sessions", overlay=true)

nySession   = input(title="New York session", type=session, defval="0800-1700")
showNy      = input(title="Display New York session?", type=bool, defval=true)
lonSession  = input(title="London session", type=session, defval="0300-1200")
showLon     = input(title="Display London session?", type=bool, defval=true)
tokSession  = input(title="Tokyo session", type=session, defval="1800-0300")
showTok     = input(title="Display Tokyo session?", type=bool, defval=true)
sydSession  = input(title="Sydney session", type=session, defval="1600-0100")
showSyd     = input(title="Display Sydney session?", type=bool, defval=true)

nyColour  = #4169E1             // royal blue
lonColour = #FF6347             // tomato
tokColour = #CD853F             // peru
sydColour = #3CB371             // medium sea green

InSession(sess) => na(time(period, sess)) == false

bgcolor(color=InSession(nySession)[1] and showNy ? nyColour : na, title="New York", transp=85)
bgcolor(color=InSession(lonSession)[1] and showLon ? lonColour : na, title="London", transp=85)
bgcolor(color=InSession(tokSession)[1] and showTok ? tokColour : na, title="Tokyo", transp=85)
bgcolor(color=InSession(sydSession)[1] and showSyd ? sydColour : na, title="Sydney", transp=85)