old_contents: import os
  import csv
  
  class CSVFile(object):
      def __init__(self, path, values):
          self.path = path
          self.values = values
  
      def write(self, results):
          field_names = self.values.keys()
          write_header = not os.path.exists(self.path)
          with open(self.path, 'a') as output_file:
              writer = csv.DictWriter(output_file, fieldnames=field_names)
              if write_header:
                  writer.writeheader()
              row = {}
              for field in self.values:
                  row[field]= self.values[field](results)
              writer.writerow(row)
  
new_contents: import os
  import csv
  
  
  class CSVFile(object):
      def __init__(self, path, values):
          self.path = path
          self.values = values
  
      def write(self, results):
          field_names = self.values.keys()
          write_header = not os.path.exists(self.path)
          with open(self.path, 'a') as output_file:
              writer = csv.DictWriter(output_file, fieldnames=field_names)
              if write_header:
                  writer.writeheader()
              row = {}
              for field in self.values:
                  row[field] = self.values[field](results)
              writer.writerow(row)
  
subject: Fix a couple of PEP8 issues