code: def    npv(ico, nci, r, n):
      
      pv_nci = 0
      for x in range(n):
          pv_nci = pv_nci + (nci/((1 + r) ** (x + 1)))
      return pv_nci - ico
docs: This capital budgeting function computes the net present
      value on a cash flow generating investment.
      ico = Initial Capital Outlay
      nci = net cash inflows per period
      r = discounted rate
      n = number of periods
      Example: npv(100000, 15000, .03, 10)