def EncodeMultipartFormData(fields, files):
	"""Encode form fields for multipart/form-data.

	Args:
		fields: A sequence of (name, value) elements for regular form fields.
		files: A sequence of (name, filename, value) elements for data to be
					uploaded as files.
	Returns:
		(content_type, body) ready for httplib.HTTP instance.

	Source:
		http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/146306
	"""
	BOUNDARY = '-M-A-G-I-C---B-O-U-N-D-A-R-Y-'
	CRLF = '\r\n'
	lines = []
	for (key, value) in fields:
		typecheck(key, str)
		typecheck(value, str)
		lines.append('--' + BOUNDARY)
		lines.append('Content-Disposition: form-data; name="%s"' % key)
		lines.append('')
		lines.append(value)
	for (key, filename, value) in files:
		typecheck(key, str)
		typecheck(filename, str)
		typecheck(value, str)
		lines.append('--' + BOUNDARY)
		lines.append('Content-Disposition: form-data; name="%s"; filename="%s"' % (key, filename))
		lines.append('Content-Type: %s' % GetContentType(filename))
		lines.append('')
		lines.append(value)
	lines.append('--' + BOUNDARY + '--')
	lines.append('')
	body = CRLF.join(lines)
	content_type = 'multipart/form-data; boundary=%s' % BOUNDARY
	return content_type, body
Encode form fields for multipart/form-data.

	Args:
		fields: A sequence of (name, value) elements for regular form fields.
		files: A sequence of (name, filename, value) elements for data to be
					uploaded as files.
	Returns:
		(content_type, body) ready for httplib.HTTP instance.

	Source:
		http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/146306