def download_file(url, dest=None, chunk_size=1024, replace="ask",
                  label="Downloading {dest_basename} ({size:.2f}MB)",
                  expected_extension=None):
    """Download a file from a given URL and display progress.

    :param dest: If the destination exists and is a directory, the filename
        will be guessed from the Content-Disposition header. If the destination
        is an existing file, the user will either be prompted to overwrite, or
        the file will be replaced (depending on the value of **replace**). If
        the destination does not exist, it will be used as the filename.
    :param int chunk_size: bytes read in at a time.
    :param replace: If `False`, an existing destination file will not be
        overwritten.
    :param label: a string which is formatted and displayed as the progress bar
        label. Variables provided include *dest_basename*, *dest*, and *size*.
    :param expected_extension: if set, the filename will be sanitized to ensure
        it has the given extension. The extension should not start with a dot
        (`.`).
    """
    dest = Path(dest or url.split("/")[-1])
    response = get(url, stream=True)
    if (dest.exists()
            and dest.is_dir()
            and "Content-Disposition" in response.headers):
        content_disposition = rfc6266.parse_requests_response(response)
        if expected_extension is not None:
            filename = content_disposition.filename_sanitized(
                expected_extension)
        filename = secure_filename(filename)
        dest = dest / filename
    if dest.exists() and not dest.is_dir():
        if (replace is False
                or replace == "ask"
                and not click.confirm("Replace {}?".format(dest))):
            return str(dest)
    size = int(response.headers.get("content-length", 0))
    label = label.format(dest=dest, dest_basename=dest.name,
                         size=size/1024.0/1024)
    with click.open_file(str(dest), "wb") as f:
        content_iter = response.iter_content(chunk_size=chunk_size)
        with click.progressbar(content_iter, length=size/1024,
                               label=label) as bar:
            for chunk in bar:
                if chunk:
                    f.write(chunk)
                    f.flush()
    return str(dest)
def get_list(arg=None):
	"""get list of messages"""
	frappe.form_dict['limit_start'] = int(frappe.form_dict['limit_start'])
	frappe.form_dict['limit_page_length'] = int(frappe.form_dict['limit_page_length'])
	frappe.form_dict['user'] = frappe.session['user']

	# set all messages as read
	frappe.db.begin()
	frappe.db.sql("""UPDATE `tabCommunication` set seen = 1
		where
			communication_type in ('Chat', 'Notification')
			and reference_doctype = 'User'
			and reference_name = %s""", frappe.session.user)

	delete_notification_count_for("Messages")

	frappe.local.flags.commit = True

	if frappe.form_dict['contact'] == frappe.session['user']:
		# return messages
		return frappe.db.sql("""select * from `tabCommunication`
			where
				communication_type in ('Chat', 'Notification')
				and reference_doctype ='User'
				and (owner=%(contact)s
					or reference_name=%(user)s
					or owner=reference_name)
			order by creation desc
			limit %(limit_start)s, %(limit_page_length)s""", frappe.local.form_dict, as_dict=1)
	else:
		return frappe.db.sql("""select * from `tabCommunication`
			where
				communication_type in ('Chat', 'Notification')
				and reference_doctype ='User'
				and ((owner=%(contact)s and reference_name=%(user)s)
					or (owner=%(contact)s and reference_name=%(contact)s))
			order by creation desc
			limit %(limit_start)s, %(limit_page_length)s""", frappe.local.form_dict, as_dict=1)