code: def encode_multipart_formdata(fields, boundary=None):
      """
      Encode a dictionary of ``fields`` using the multipart/form-data mime format.
  
      :param fields:
          Dictionary of fields or list of (key, value) field tuples.  The key is
          treated as the field name, and the value as the body of the form-data
          bytes. If the value is a tuple of two elements, then the first element
          is treated as the filename of the form-data section.
  
          Field names and filenames must be str.
  
      :param boundary:
          If not specified, then a random boundary will be generated using
          :func:`mimetools.choose_boundary`.
      """
      # copy requests imports in here:
      from io import BytesIO
      from requests.packages.urllib3.filepost import (
          choose_boundary,
          writer,
          b,
          get_content_type,
      )
  
      body = BytesIO()
      if boundary is None:
          boundary = choose_boundary()
  
      for fieldname, value in iter_fields(fields):
          body.write(b("--%s\r\n" % (boundary)))
  
          if isinstance(value, tuple):
              filename, data = value
              writer(body).write(
                  'Content-Disposition: form-data; name="%s"; '
                  'filename="%s"\r\n' % (fieldname, filename)
              )
              body.write(
                  b(
                      "Content-Type: %s\r\n\r\n"
                      % (get_content_type(filename))
                  )
              )
          else:
              data = value
              writer(body).write(
                  'Content-Disposition: form-data; name="%s"\r\n'
                  % (fieldname)
              )
              body.write(b"Content-Type: text/plain\r\n\r\n")
  
          if isinstance(data, int):
              data = str(data)  # Backwards compatibility
          if isinstance(data, str):
              writer(body).write(data)
          else:
              body.write(data)
  
          body.write(b"\r\n")
  
      body.write(b("--%s--\r\n" % (boundary)))
  
      content_type = b("multipart/form-data; boundary=%s" % boundary)
  
      return body.getvalue(), content_type
  
imports: import getpass
  import json
  import os
  import re
  import sys
  import requests
label_desc: Use image node_id 15 for calling a global function with example usage: encode_multipart_formdata(fields, boundary) and returns: body,  content_type