how do I mention a user'id using discord.py code example

Example 1: discord py get user by id

user = bot.get_user(user_id)

Example 2: discord.py mention user

#discord.py rewrite
#python 3+
bot.command(name='pingme', help='pings the author of the message')
async def pingme(ctx):
	#to get a member from a 'ctx' object is ctx.author
	#from there its .mention will mention (ping) the user
	#also there are others like .id
	await ctx.send(ctx.author.mention)