title: List of Column names having at least 1 Null value and total number of null values corresponding to each column pandas
body: <p>Hi I have a code which prints column names along with null values in columns:</p>
  
  <pre><code>A    B     C    D
  1    1     4    NAN
  2    2     5     NAN
  3    NAN   6     NAN
  </code></pre>
  
  <p><strong>My Code</strong></p>
  
  <pre><code>[IN]res = list(df.isnull().sum().items())
  [IN]print(res)
  </code></pre>
  
  <p><strong>Current Output</strong></p>
  
  <pre><code>[('A', 0), ('B', 1), ('C', 0), ('D', 3)]
  </code></pre>
  
  <p><strong>Expected output:</strong></p>
  
  <pre><code>[('B', 1), ('D', 3)]
  </code></pre>
  
  <p>So basically I wish to remove columns where there are 0 null values and <strong>return only columns with at least 1 null value.</strong></p>