title: Why doesn't this while loop break when iterating through pandas dataframe?
body: <p>When I run the code it seems to iterate through the whole dataframe twice and it ignores the while condition</p>
  
  <pre class="lang-py prettyprint-override"><code>import pandas as pd
  
  a = 0
  
  sales = [
           {'account': 'Jones LLC', 'Jan': 150, 'Feb': 200, 'Mar': 140},
           {'account': 'Alpha Co',  'Jan': 200, 'Feb': 210, 'Mar': 215},
           {'account': 'Blue Inc',  'Jan': 50,  'Feb': 90,  'Mar': 95 },
           {'account': 'Blue Inc',  'Jan': 50,  'Feb': 90,  'Mar': 95 },
           {'account': 'Blue Inc',  'Jan': 50,  'Feb': 90,  'Mar': 95 },
           {'account': 'Blue Inc',  'Jan': 50,  'Feb': 90,  'Mar': 95 }
          ]
  
  df = pd.DataFrame(sales)
  
  while a &lt;= 6:
      for index, row in df.iterrows():
          df.loc[index, 'a'] = a
          print(a, index)
          a += 1
  
  df
  </code></pre>