My dataframe from xlsx:
1  NaN  A     B     C
2  X   '1'   '11'  '111'
3  Y   '2'   '22'  '222'
4  Z   '3'   '33'  '333'
How to use pandas to convert to dict type like:
{X:{'A':'1','B':'11','C':'111'},
 Y:{'A':'2','B':'22','C':'222'},
 Z:{'A':'3','B':'33','C':'333'}}