docstr: Determine if there are bytes left to write.
  
  :returns: bool -- ``True`` if there are bytes left to write, otherwise
      ``False``
code: def bytes_left_to_write(self):
      """Determine if there are bytes left to write.
  
      :returns: bool -- ``True`` if there are bytes left to write, otherwise
          ``False``
      """
      to_read = 0
      if self.headers_unread:
          to_read += len(self.headers)
  
      return (to_read + total_len(self.body)) > 0
  
imports: import contextlib
  import io
  import os
  from uuid import uuid4
  import requests
  from .._compat import fields
label_desc: Use image node_id 3 for calling the Part obj's underlying member method code with example usage: obj.bytes_left_to_write() and returns: unknown