mul() Broadcast across levels from Multi Index
http://stackoverflow.com/questions/31435632/mul-broadcast-levels-from-multi-index

Attempting to use a multiply operation with a multi index.

```
import pandas as pd
import numpy as np

d = {'Alpha': [1,2,3,4,5,6,7,8,9]
   ,'Beta':tuple('ABCDEFGHI')
   ,'C': np.random.randint(1,10,9)
   ,'D': np.random.randint(100,200,9)
 }

df = pd.DataFrame(d)
df.set_index(['Alpha','Beta'],inplace=True)
df = df.stack() #it's now a series
df.index.names = df.index.names[:-1] + ['Gamma']

ser = pd.Series(data = np.random.rand(9))
ser.index = pd.MultiIndex.from_tuples(zip(range(1,10),np.repeat('C',9)))
ser.index.names = ['Alpha','Gamma']

print df
print ser

foo = df.mul(ser,axis=0,level = ['Alpha','Gamma'])
So my dataframe which became a series looks like

Alpha  Beta  Gamma
1      A     C          7
             D        188
2      B     C          7
             D        110
3      C     C          2
             D        124
4      D     C          4
             D        153
5      E     C          9
             D        178
6      F     C          6
             D        196
7      G     C          1
             D        156
8      H     C          1
             D        184
9      I     C          3
             D        169
And my series looks like

Alpha  Gamma
1      C       0.8731
2      C       0.6347
3      C       0.4688
4      C       0.5623
5      C       0.4944
6      C       0.5234
7      C       0.9946
8      C       0.7815
9      C       0.1219
```

In my multiple operation I want to broadcast on index levels 'Alpha' and 'Gamma'

but i get this error message TypeError: Join on level between two MultiIndex objects is ambiguous
