Running examples in ‘ukgasapi-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: dataItemExplorer
> ### Title: Data Item Explorer API
> ### Aliases: dataItemExplorer
> 
> ### ** Examples
> 
> # Specify the data item(s) to enquire from API
> dataitems <- c("Storage Injection, Actual",
+                "Storage Withdrawal, Actual")
> 
> # Initialise API (requires internet connection for this step)
> response <- dataItemExplorer(dataitems,
+                              fromdate = "2013-10-01",
+                              todate="2015-09-30")
*   Trying 104.18.79.103...
* TCP_NODELAY set
* Connected to marketinformation.natgrid.co.uk (104.18.79.103) port 443 (#0)
* found 596 certificates in /etc/ssl/certs
* ALPN, offering http/1.1
* SSL connection using TLS1.2 / ECDHE_ECDSA_CHACHA20_POLY1305
* 	 server certificate verification OK
* 	 server certificate status verification SKIPPED
* 	 common name: ssl897922.cloudflaressl.com (matched)
* 	 server certificate expiration date OK
* 	 server certificate activation date OK
* 	 certificate public key: EC/ECDSA
* 	 certificate version: #3
* 	 subject: OU=Domain Control Validated,OU=PositiveSSL Multi-Domain,CN=ssl897922.cloudflaressl.com
* 	 start date: Mon, 25 Jun 2018 00:00:00 GMT
* 	 expire date: Sat, 18 May 2019 23:59:59 GMT
* 	 issuer: C=GB,ST=Greater Manchester,L=Salford,O=COMODO CA Limited,CN=COMODO ECC Domain Validation Secure Server CA 2
* 	 compression: NULL
* ALPN, server accepted to use http/1.1
> POST /MIPIws-public/public/publicwebservice.asmx HTTP/1.1
Host: marketinformation.natgrid.co.uk
Accept: text/xml
Content-Type: application/soap+xml; charset=utf-8
Content-Length: 655

* upload completely sent off: 655 out of 655 bytes
< HTTP/1.1 502 Bad Gateway
< Date: Mon, 03 Dec 2018 23:01:05 GMT
< Content-Type: text/html; charset=UTF-8
< Transfer-Encoding: chunked
< Connection: keep-alive
< Set-Cookie: __cfduid=d5ad619132ea30c98aa67d66a20cb4e061543878031; expires=Tue, 03-Dec-19 23:00:31 GMT; path=/; domain=.natgrid.co.uk; HttpOnly
< Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
< Set-Cookie: cf_use_ob=0; path=/; expires=Mon, 03-Dec-18 23:01:35 GMT
< Expires: Thu, 01 Jan 1970 00:00:01 GMT
< Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
< Pragma: no-cache
< Server: cloudflare
< CF-RAY: 4839a6608a625996-VIE
< 
* Connection #0 to host marketinformation.natgrid.co.uk left intact
Entity 'bull' not defined
Entity 'bull' not defined
Entity 'bull' not defined
Error: 1: Entity 'bull' not defined
2: Entity 'bull' not defined
3: Entity 'bull' not defined
Execution halted