title: Count frequency of item in a list of tuples
body: <p>I have a list of tuples as shown below. I have to count how many items have a number greater than 1. The code that I have written so far is very slow. Even if there are around 10K tuples, if you see below example string appears two times, so i have to get such kind of strings. My question is what is the best way to achieve the count of strings here by iterating over the generator</p>
  
  <p>List:</p>
  
  <pre><code> b_data=[('example',123),('example-one',456),('example',987),.....]
  </code></pre>
  
  <p>My code so far:</p>
  
  <pre><code>blockslst=[]
  for line in b_data:
      blockslst.append(line[0])
  
  blocklstgtone=[]
  for item in blockslst:
      if(blockslst.count(item)&gt;1):
          blocklstgtone.append(item)
  </code></pre>