title: KeyError: 'Date'
body: <pre><code>import pandas as pd
  import numpy as np
  from nsepy import get_history
  import datetime as dt
  start = dt.datetime(2015, 1, 1)
  
  end = dt.datetime.today()
  
  infy = get_history(symbol='INFY', start = start, end = end)
  infy.index = pd.to_datetime(infy.index)
  infy.head()
  infy_volume = infy.groupby(infy['Date'].dt.year).reset_index().Volume.sum().
  </code></pre>
  
  <blockquote>
    <p>"Error showed as Date", but Infy_volume should be a multi-index series
    with two levels of index - Year and Month</p>
  </blockquote>
  
  <p>.</p>