I want to create a dictionary from the values, i get from excel cells, 
My code is below,

```
wb = xlrd.open_workbook('foo.xls')
sh = wb.sheet_by_index(2)   
for i in range(138):
    cell_value_class = sh.cell(i,2).value
    cell_value_id = sh.cell(i,0).value

```

and I want to create a dictionary, like below, that consists of the values coming from the excel cells;

```
{'class1': 1, 'class2': 3, 'class3': 4, 'classN':N}

```

Any idea on how I can create this dictionary?