[Tutor] Strange error

[jarod_v6 at libero.it]

HI!!
This is my list:

In [378]: type(Span)
Out[378]: list

In [379]: Span
Out[379]: 
[['M02898:39:000000000-AH4BK:1:2107:17412:10850',
  'M02898:39:000000000-AH4BK:1:2117:15242:18766',
  'M02898:39:000000000-AH4BK:1:1112:21747:21214',
  'M02898:39:000000000-AH4BK:1:2112:5119:9813',
  'M02898:39:000000000-AH4BK:1:1102:26568:5630',
  'M02898:39:000000000-AH4BK:1:2118:19680:11792',
  'M02898:39:000000000-AH4BK:1:1103:5469:6578',
  'M02898:39:000000000-AH4BK:1:2101:13087:20965',
  'M02898:39:000000000-AH4BK:1:1103:28031:13653',
  'M02898:39:000000000-AH4BK:1:1103:8013:21346',
  'M02898:39:000000000-AH4BK:1:1107:9189:22557',
  'M02898:39:000000000-AH4BK:1:2118:21263:23091',
  'M02898:39:000000000-AH4BK:1:1115:12279:20054',
  'M02898:39:000000000-AH4BK:1:1102:19433:17489',
  'M02898:39:000000000-AH4BK:1:1110:14533:11792',
  'M02898:39:000000000-AH4BK:1:2106:18027:12878',
  'M02898:39:000000000-AH4BK:1:1104:4408:6824',
  'M02898:39:000000000-AH4BK:1:2101:5678:7400']]

I have this error


In [381]: len(Span)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-381-6f83caae0041> in <module>()
----> 1 len(Span)

TypeError: 'str' object is not callable



Why??? IS a list!!!