title: How to write to CSV and not overwrite past text
body: <p>The code below is what I have so far. When it writes to the .csv it overwrites what I had previously written in the file.How can I write to the file in such a way that it doesn't erase my previous text.(The objective of my code is to have a person enter their name and have the program remember them)</p>
  
  <pre><code>def main(src):
      try:
          input_file = open(src, "r")
      except IOError as error:
          print("Error: Cannot open '" + src + "' for processing.")
      print("Welcome to Learner!")
      print("What is your name? ")
      name = input()
      for line in input_file:
          w = line.split(",")
          for x in w:    
              if x.lower() == name.lower():
                  print("I remember you "+ name.upper())
              else:
                  print("NO")
                  a = open("learner.csv", "w")
                  a.write(name)
                  a.close()
                  break
  if __name__ == "__main__":
      main("learner.csv")
  </code></pre>