code: def add_sample_meta(self,
                          source,
                          reference,
                          method='',
                          filename='',
                          md5='',
                          sha1='',
                          sha256='',
                          size='',
                          mimetype='',
                          campaign='',
                          confidence='',
                          description='',
                          bucket_list=[]):
          
          data = {
              'api_key': self.api_key,
              'username': self.username,
              'source': source,
              'reference': reference,
              'method': method,
              'filename': filename,
              'md5': md5,
              'sha1': sha1,
              'sha256': sha256,
              'size': size,
              'mimetype': mimetype,
              'upload_type': 'meta',
              'campaign': campaign,
              'confidence': confidence,
              'bucket_list': ','.join(bucket_list),
          }
          r = requests.post('{0}/samples/'.format(self.url),
                            data=data,
                            verify=self.verify,
                            proxies=self.proxies)
          if r.status_code == 200:
              result_data = json.loads(r.text)
              return result_data
          else:
              log.error('Error with status code {0} and message '
                        '{1}'.format(r.status_code, r.text))
          return None
docs: Adds a metadata sample. To add an actual file, use add_sample_file.
  
          Args:
              source: Source of the information
              reference: A reference where more information can be found
              method: The method for obtaining the sample.
              filename: The name of the file.
              md5: An MD5 hash of the file.
              sha1: SHA1 hash of the file.
              sha256: SHA256 hash of the file.
              size: size of the file.
              mimetype: The mimetype of the file.
              campaign: An associated campaign
              confidence: The campaign confidence
              bucket_list: A list of bucket list items to add
              upload_type: Either 'file' or 'meta'
          Returns:
              A JSON sample object or None if there was an error.