code: def read(self, src):
          
          geojson = None
          if not self.is_valid_src(src):
              error = "File < {0} > does not exists or does start with 'http'."
              raise ValueError(error.format(src))
          if not self.is_url(src):
              return open(src, 'r').read().decode('latin-1').encode('utf-8')
          tmp = self.get_location(src)
          # if src poits to url that was already downloaded
          # read from local file instead
          if os.path.isfile(tmp):
              with open(tmp, 'r') as f:
                  return f.read()
          # download file and write to local filesystem before returning
          response = urllib2.urlopen(src)
          data = response.read().decode('latin-1').encode('utf-8')
          with open(tmp, 'w') as f:
              f.write(data)
              return data
docs: Download GeoJSON file of US counties from url (S3 bucket)