docstr: Build up the MIME payload for the POST data
docstr_tok: ["Build","up","the","MIME","payload","for","the","POST","data"]
code: def _build_multipart(cls, data):
      """
      Build up the MIME payload for the POST data
      """
      boundary = "--------------GHSKFJDLGDS7543FJKLFHRE75642756743254"
      sep_boundary = b"\n--" + boundary.encode("ascii")
      end_boundary = sep_boundary + b"--"
      end_items = (
          end_boundary,
          b"\n",
      )
      builder = functools.partial(
          cls._build_part,
          sep_boundary=sep_boundary,
      )
      part_groups = map(builder, data.items())
      parts = itertools.chain.from_iterable(part_groups)
      body_items = itertools.chain(parts, end_items)
      content_type = "multipart/form-data; boundary=%s" % boundary
      return b"".join(body_items), content_type
  
imports: from base64 import standard_b64encode
  from distutils import log
  from distutils.errors import DistutilsOptionError
  import os
  import zipfile
  import tempfile
  import shutil
  import itertools
  import functools
  import http.client
  import urllib.parse
  from .._importlib import metadata
  from ..warnings import SetuptoolsDeprecationWarning
  from .upload import upload
label_desc: Use image node_id 7 for calling the upload_docs obj's underlying member method code with example usage: obj._build_multipart(cls, data) and returns: bytes,  content_type