title: openpyxl iterate through cells of column => TypeError: 'generator' object is not subscriptable
body: <p>i I want to loop over all values op a column, to safe them as the key in a dict. As far as i know, everything is ok, but python disagrees.</p>
  
  <p>So my question is: "what am i doing wrong?"</p>
  
  <pre><code>&gt;&gt;&gt; wb = xl.load_workbook('/home/x/repos/network/input/y.xlsx')
  &gt;&gt;&gt; sheet = wb.active
  &gt;&gt;&gt; for cell  in sheet.columns[0]:
  ...     print(cell.value)
  ... 
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  TypeError: 'generator' object is not subscriptable
  </code></pre>
  
  <p>I must be missing something, but after a few hours of trying, I must throw in the towle and call in the cavalecry ;)</p>
  
  <p>thanks in advance for all the help!</p>
  
  <p>===================================================================</p>
  
  <p>@Charlie Clark: thanks for taking the time to answer. The thing is, I need the first column as keys in a dict, afterwards, I need to do</p>
  
  <pre><code>for cell  in sheet.columns[1:]:
  </code></pre>
  
  <p>so, while it would resolve my issue, it would come back to me a few lines later, in my code. I will use your suggestion in my code to extract the keys.</p>
  
  <p>The question I mostly have is: </p>
  
  <p>why doesn't it work, I am sure I used this code snippet before and this is also how, when googling, people are suggesting to do it.</p>
  
  <p>==========================================================================</p>
  
  <pre><code>&gt;&gt;&gt; for column in ws.iter_cols(min_col = 2):
  ...     for cell in column:
  ...             print(cell.value)
  </code></pre>
  
  <p>goes over all columns of the sheet, except the first. Now, I still need to exclude the first 3 rows </p>