runAPI

   public static List<sfLimit> runAPI(){
		
   		//Get a token
		String clientId = Label.Limits_Connected_App_Client;
		String clientSecret = Label.Limits_Connected_App_Key;
		String username= Label.Limits_Username;
		String password= Label.Limits_PW;
		//using this request body we'll make API call
		String reqbody = 'grant_type=password&client_id='+clientId+'&client_secret='+clientSecret+'&username='+username+'&password='+password;
   		String sfdcURL = URL.getSalesforceBaseUrl().toExternalForm(); 
		Http h = new Http();
		HttpRequest req = new HttpRequest();
		req.setBody(reqbody);
		req.setMethod('POST');
		String endpoint = Utilities.isProduction() ? 'https://login.salesforce.com/services/oauth2/token' : 'https://test.salesforce.com/services/oauth2/token';
		system.debug(endpoint);
		req.setEndpoint(endpoint);
		HttpResponse res = h.send(req);
		OAuth2 objAuthInfo =(OAuth2)JSON.deserialize(res.getbody(), OAuth2.class);
		system.debug(objAuthInfo);
		String restAPIURL = sfdcURL + '/services/data/v41.0/limits';
		HttpRequest httpRequest = new HttpRequest();
		httpRequest.setMethod('GET');          
		httpRequest.setHeader('Authorization', 'Bearer ' + objAuthInfo.access_token); 
		httpRequest.setEndpoint(restAPIURL);
		List<sfLimit> l = new List<sfLimit>();
		String response = '';
		try {
			 Http http = new Http();
			 HttpResponse httpResponse = http.send(httpRequest);  
			if (httpResponse.getStatusCode() == 200 ) {
			 	String JSONContent = httpResponse.getBody();
			 	System.debug(JSONContent);
			 	JSONParser parserJira = JSON.createParser(JSONContent);
			 	String lName;
			 	String innerName;
			 	Integer Max;
				Integer Remaining;
				String text;
				Integer innerMax;
				Integer innerRemaining;
				while (parserJira.nextToken() != null) {
					if (parserJira.getCurrentToken() == JSONToken.FIELD_NAME) {
						Max = null;
						Remaining = null;
						lName = null;
						text = parserJira.getText();
						lName = text;
						if (parserJira.nextToken() != JSONToken.VALUE_NULL) {
							if (text == 'Max') {
								Max = parserJira.getIntegerValue();
							} else if (text == 'Remaining') {
								Remaining = parserJira.getIntegerValue();
							} else {
								//inner Limits
								if(parserJira.nextToken() != JSONToken.END_OBJECT){
									if(parserJira.getText() == 'Max'){
										parserJira.nextToken();
										innerMax = parserJira.getIntegerValue();
										parserJira.nextToken();
									}
									if(parserJira.getText() == 'Remaining'){
										parserJira.nextToken();
										innerRemaining = parserJira.getIntegerValue();
									}
								}
								Max = innerMax;
								Remaining = innerRemaining;
								consumeObject(parserJira);
							}
						}
					}
					sfLimit sfl = new sfLimit(text,Max,Remaining);
					system.debug(sfl);
					l.add(sfl);
				}
					system.debug(l);
					return l;
			} else {  
				   System.debug(' httpResponse ' + httpResponse.getBody() );  
				   throw new CalloutException( httpResponse.getBody() );
				   return null;  
			}
		} catch( System.Exception e) {  
				 System.debug('ERROR: '+ e);  
				 throw e;
				 return null;
		}  
	}