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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def change_password(ctx):
 """Change password of an existing user"""


    username, passhash = _get_credentials(ctx.obj['username'],
                                          ctx.obj['password'],
                                          ctx.obj['db'])

    change_user = ctx.obj['db'].objectmodels['user'].find_one({
        'name': username
    })
    if change_user is None:
        log('No such user', lvl=warn)
        return

    change_user.passhash = passhash
    change_user.save()

    log("Done")