docs: def encode_hdr(self, boundary):
          """Returns the header of the encoding of this parameter"""
          boundary = encode_and_quote(boundary)
  
          headers = ["--%s" % boundary]
  
          if self.filename:
              disposition = 'form-data; name="%s"; filename="%s"' % (self.name,
                                                                     self.filename)
          else:
              disposition = 'form-data; name="%s"' % self.name
  
          headers.append("Content-Disposition: %s" % disposition)
  
          if self.filetype:
              filetype = self.filetype
          else:
              filetype = "text/plain; charset=utf-8"
  
          headers.append("Content-Type: %s" % filetype)
  
          headers.append("")
          headers.append("")
  
          return "\r\n".join(headers)