code: def select(yerrs, amps, amp_errs, widths):
      
      keep_1 = np.logical_and(amps < 0, widths > 1)
      keep_2 = np.logical_and(np.abs(amps) > 3*yerrs, amp_errs < 3*np.abs(amps))
      keep = np.logical_and(keep_1, keep_2)
      return keep
docs: criteria for keeping an object