Checks if the User with $id exists

@param string $id Identifier of the possible content

@return boolean true if it exists, false if not
320348
public function checkUserExistenceById( $id )
    {
        /** @var \eZ\Publish\API\Repository\Repository $repository */
        $repository = $this->getRepository();
        $userService = $repository->getUserService();

        return $repository->sudo(
            function() use( $id, $userService )
            {
                // attempt to load the user with the id
                try
                {
                    $userService->loadUser( $id );
                    return true;
                }
                catch ( ApiExceptions\NotFoundException $e )
                {
                    return false;
                }
            }
        );
    }
698013
public function exists($id, $version = null)
    {
        $list = $this->getList(array('id' => $id, 'version' => $version));
        return !empty($list);
    }
169061
public function has($id)
    {
        $id = $this->normalizeId($id);

        return isset($this->definitions[$id]) || isset($this->aliasDefinitions[$id]) || parent::has($id);
    }
1281380
private function checkSessionId(string $id) : bool
    {
        if (preg_match('/^[A-Za-z0-9]+$/', $id) !== 1) {
            return false;
        }

        if (strlen($id) !== $this->idLength) {
            return false;
        }

        return true;
    }
920490
public function providerHas(/*# string */ $id)/*# : bool */
    {
        foreach ($this->providers as $provider) {
            if ($provider->has($id)) {
                return true;
            }
        }
        return false;
    }
1268246
public function existsEmployee($id = null) {
		if (empty($id)) {
			return false;
		}

		$conditions = $this->_getConditionsForEmployee($id);
		$callbacks = false;
		$this->recursive = -1;

		return (bool)$this->find('count', compact('count', 'conditions', 'callbacks'));
	}
1342768
public function has($id) {
		$source = $id;
		while (is_string($source) && isset($this->getter[$source])) {
			$source = $this->getter[$source];
		}
		if (!is_string($source)) {
			return $source instanceof \Closure;
		} else {
			if (isset($this->instance[$source]) || class_exists($source)) {
				return true;
			}
			return false;
		}
	}
155451
public function activate($id)
    {
        $user = $this->findById($id);

        try
        {
            if ( $user->attemptActivation($user->getActivationCode()) )
            {
                $this->event->fire('users.activate',array($user));
                return true;
            }
        }
        catch (UserAlreadyActivatedException $e){}


        return false;
    }
1339380
public function has($id)
    {
        $id = (string) $id;

        return isset($this->definitions[$id]) || isset($this->aliasDefinitions[$id]) || parent::has($id);
    }
651319
public function has($id)
    {
        // second argument
        $withAutowiring = func_num_args() > 1 ? (bool) func_get_arg(1) :
            $this->autowiring;

        // return FALSE if $id not a string
        return is_string($id) && (
            // found in definitions ?
            isset($this->services[$id])  ||

            // Or in definition providers ?
            $this->hasInProvider($id) ||

            // Or with id autowired ?
            $this->autoWiringId($id, $withAutowiring)
        ) ? true : false;
    }
271299
public function exists($id)
    {
        if (!$this->isTtlMode()) {
            return file_exists($this->getPath($id));
        } else {
            return $this->get($id) !== false;
        }
    }
1368620
protected function exists(int $id = 0): bool
    {
        return (bool)@shmop_open($id ? $id : $this->id, 'a', 0, 0);
    }
115762
public function exists($id)
    {
        try {
            return !!$this->resource->hExists(static::CACHE_KEY, $id);
        } catch (ConnectionException $e) {
            return false;
        }
    }
204955
public function findById($id) {
    $dataConnection = $this->app->getDataConnection($this->connection);
    $result = $dataConnection->findOneByField($this->idColumn, $dataConnection->convertToNativeId($id),
      $this->table, $this->readFields);
    if ($result == NULL) {
      return FALSE;
    }
    $this->load($result);
    return TRUE;
  }
1069513
public function hasTagById( $id )
	{
		$xpath	= new DomXPath( $this->document );
		$query	= "//*[@id = '$id']";
		$nodes	= $xpath->query( $query );
		return (bool) $nodes->length;
	}
606923
public function offsetExists($id)
    {
        if (isset($this->delegates[$id])) {
            return true;
        }
        // @codingStandardsIgnoreStart
        @trigger_error(
            'isset service: The pimple based DIC is deprecated, use the symfony DIC in new projects.',
            E_USER_DEPRECATED
        );
        // @codingStandardsIgnoreEnd

        return parent::offsetExists($id);
    }
1034518
public function hasDocument(string $id): bool
    {
        if (isset($this->documents[$id])) {
            return true;
        }

        $path = $this->getDocumentPath($id);

        if ($this->filesystem->has($path)) {
            $info = $this->filesystem->getMetadata($path);

            return $info['type'] === 'file';
        }

        return false;
    }