code: def write(self, b):
          
  
          if not isinstance(b, _BINARY_TYPES):
              raise TypeError(
                  "input must be one of %r, got: %r" % (_BINARY_TYPES, type(b)))
  
          self._buf.write(b)
          self._total_bytes += len(b)
  
          if self._buf.tell() >= self._min_part_size:
              self._upload_next_part()
  
          return len(b)
docs: Write the given bytes (binary string) to the S3 file.
  
          There's buffering happening under the covers, so this may not actually
          do any HTTP transfer right away.