old_contents: #!/usr/bin/python
  
  def parse(fileToParse, linesToParse, stringsToParse):
  	fileText = open(fileToParse).readlines()
  	
  	for lineToParse, stringToParse in zip(linesToParse, stringsToParse):
  		stringToParse = stringToParse.replace(' ','')
  		stringToParse = stringToParse.replace('\n', '')
  		
  		stringParsed = fileText[lineToParse-1]
  		stringParsed = stringParsed.replace('\n', '')
  		stringParsed = stringParsed.replace(' ','')
  		
  		if(stringParsed != stringToParse):
  			return lineToParse
  		
  	return None
  
new_contents: """String parsing and matching utilities.
  
  Functions:
  parse -- parse lines in exercise file and return wrong line or None.
  """
  
  
  def parse(fileToParse, linesToParse, stringsToParse):
      """parse lines in exercise file, match list and return line differences.
  
      Keyword arguments
      fileToParse -- the complete path to the filename to parse.
      linesToParse -- a list of line numbers to parse and check.
      stringsToParse -- a list of the values that linesToParse must match.
      """
      fileText = open(fileToParse).readlines()
  
      for lineToParse, stringToParse in zip(linesToParse, stringsToParse):
          stringToParse = stringToParse.replace(' ', '')
          stringToParse = stringToParse.replace('\n', '')
  
          stringParsed = fileText[lineToParse-1]
          stringParsed = stringParsed.replace('\n', '')
          stringParsed = stringParsed.replace(' ', '')
  
          # If a line to check differs, return its line number
          if(stringParsed != stringToParse):
              return lineToParse
  
      # Reached if all lines match
      return None
  
subject: Document and correct style of parser