code: def _validate_field_headers(reader):
          
  
          link = 'tools.ietf.org/html/rfc4180#section-2'
  
          for field in reader.fieldnames:
              if not isinstance(field, str):
                  fail('All headers in your CSV payload must be '
                       'strings.', link)
  
          if 'type' not in reader.fieldnames:
              fail('A type header must be present in your CSV '
                   'payload.', link)
docs: Perform some validations on the CSV headers
  
          A `type` field header must be present & all field
          headers must be strings.
  
          :param reader: csv reader object