title: Losing "+" in phone numbers , when converting csv to txt in Pandas
body: <p>Phone number "+49374425070" is getting converted to "49374425070.0" when i try to use "to_csv".</p>
  
  <pre><code>source.to_csv('CVV'+'_source.txt',sep = '\t', index = False ,encoding='utf-8',quoting=csv.QUOTE_NONE)
  
  import pandas as pd
  import csv
  
  
  #Source
  source = pd.read_csv('source2.csv') #source csv name
  source.to_csv('CVV'+'_source.txt',sep = '\t', index = False ,encoding='utf-8',quoting=csv.QUOTE_NONE)#float_format='%.0f'
  
  print('archive.txt and source.txt generated')
  </code></pre>