fn main() {
    let mut a: u8 = 0;
    let mut b: u8 = 1;
    println!("{}", a);
    while b <= 100 {
        println!("{}", b);
        b = a + b;
        a = b - a;
    }
}

Output:

0
1
1
2
3
5
8
13
21
34
55
89

if __FILE__ == $0
  limit = Integer(ARGV[0])
  a = 0
  b = 1
  puts a
  while b < limit
    puts b
    b = a + b
    a = b - a
  end
end

import os

limit = int(os.environ['FIB_LIMIT'])
a = 0
b = 1
print(a)
while b < limit:
    print(b)
    b = a + b
    a = b - a

[section]
a=1
b=2

; here is a comment
[another_section]
c=3
d=4
e=5

<?xml version="1.0" encoding="UTF-8"?>
    <startminimized value="False">
  <width value="1024">
  <height value = "768">
  <dummy />
  <plugin>
    <name value="Show Warning Message Box">
    <dllfile value="foo.dll">
    <method value = "warning">
  </plugin>
  <plugin>
    <name value="Show Error Message Box">
    <dllfile value="foo.dll">
    <method value = "error">
  </plugin>
  <plugin>
    <name value="Get Random Number">
    <dllfile value="bar.dll">
        <method value = "random">
  </plugin>
</xml>

{
  "firstName": "John",
  "lastName": "Smith",
  "age": 25,
  "address": {
    "streetAddress": "21 2nd Street",
    "city": "New York",
    "state": "NY",
    "postalCode": "10021"
  },
  "phoneNumber": [
    {
      "type": "home",
      "number": "212 555-1234"
    },
    {
      "type": "fax",
      "number": "646 555-4567"
    }
  ],
  "gender": {
    "type": "male"
  }
}

# sequencer protocols for Laser eye surgery
---
- step:  &id001                  # defines anchor label &id001
    instrument:      Lasik 3000
    pulseEnergy:     5.4
    pulseDuration:   12
    repetition:      1000
    spotSize:        1mm

- step: &id002
    instrument:      Lasik 3000
    pulseEnergy:     5.0
    pulseDuration:   10
    repetition:      500
    spotSize:        2mm
- step: *id001                   # refers to the first step (with anchor &id001)
- step: *id002                   # refers to the second step
- step:
    <<: *id001
    spotSize: 2mm                # redefines just this key, refers rest from &id001
- step: *id002

# This is how to comment in TOML.

title = "A TOML Example"

[owner]
name = "Gigi Sayfan"
dob = 1968-09-28T07:32:00-08:00 # First class dates

# Simple section with various data types
[kubernetes]
api_server = "192.168.1.1"
ports = [ 80, 443 ]
connection_max = 5000
enabled = true

# Nested section
[servers]

  # Indentation (tabs and/or spaces) is optional
  [servers.alpha]
  ip = "10.0.0.1"
  dc = "dc-1"

  [servers.beta]
  ip = "10.0.0.2"
  dc = "dc-2"

[clients]
data = [ ["gamma", "delta"], [1, 2] ]

# Line breaks are OK when inside arrays
hosts = [
  "alpha",
  "omega"
]

user       www www;  ## Default: nobody
worker_processes  5;  ## Default: 1
error_log  logs/error.log;
pid        logs/nginx.pid;
worker_rlimit_nofile 8192;

events {
  worker_connections  4096;  ## Default: 1024
}

http {
  include    conf/mime.types;
  include    /etc/nginx/proxy.conf;
  include    /etc/nginx/fastcgi.conf;
  index    index.html index.htm index.php;

  default_type application/octet-stream;
  log_format   main '$remote_addr - $remote_user [$time_local]  $status '
    '"$request" $body_bytes_sent "$http_referer" '
    '"$http_user_agent" "$http_x_forwarded_for"';
  access_log   logs/access.log  main;
  sendfile     on;
  tcp_nopush   on;
  server_names_hash_bucket_size 128; # this seems to be required for some vhosts

  server { # php/fastcgi
    listen       80;
    server_name  domain1.com www.domain1.com;
    access_log   logs/domain1.access.log  main;
    root         html;

    location ~ \.php$ {
      fastcgi_pass   127.0.0.1:1025;
    }
  }
}

$ cat ~/.kube/config
apiVersion: v1
clusters:
- cluster:
 certificate-authority: /Users/gigi.sayfan/.minikube/ca.crt
 server: https://192.168.99.121:8443
 name: minikube
contexts:
- context:
 cluster: minikube
 user: minikube
 name: minikube
current-context: minikube
kind: Config
preferences: {}
users:
- name: minikube
 user:
 client-certificate: /Users/gigi.sayfan/.minikube/client.crt
 client-key: /Users/gigi.sayfan/.minikube/client.key

apiVersion: v1
kind: ConfigMap
metadata:
  name: link-service-config
  namespace: default
data:
  MAX_LINKS_PER_USER: "10"
  PORT: "8080"

apiVersion: apps/v1
kind: Deployment
metadata:
  name: link-manager
  labels:
    svc: link
    app: manager
spec:
  replicas: 1
  selector:
    matchLabels:
      svc: link
      app: manager
  template:
    metadata:
      labels:
        svc: link
        app: manager
    spec:
      containers:
      - name: link-manager
        image: g1g1/delinkcious-link:0.2
        ports:
        - containerPort: 8080
      envFrom:
      - configMapRef:
          name: link-manager-config

MAX_LINKS_PER_PAGE=10
PORT=9090

port := os.Getenv("PORT")
if port == "" {
   port = "8080"
}

maxLinksPerUserStr := os.Getenv("MAX_LINKS_PER_USER")
if maxLinksPerUserStr == "" {
   maxLinksPerUserStr = "10"
}

func runLinkService(ctx context.Context) {
   // Set environment
   err := os.Setenv("PORT", "8080")
   check(err)

   err = os.Setenv("MAX_LINKS_PER_USER", "10")
   check(err)

   runService(ctx, ".", "link_service")
}

func runSocialGraphService(ctx context.Context) {
   err := os.Setenv("PORT", "9090")
   check(err)

   runService(ctx, "../social_graph_service", "social_graph_service")
}

$ kubectl create configmap test --dry-run --from-literal=a=1 --from-literal=b=2 -o yaml
apiVersion: v1
data:
 a: "1"
 b: "2"
kind: ConfigMap
metadata:
 creationTimestamp: null
 name: test

superhero: Doctor Strange
villain: Thanos

$ kubectl create configmap file-config --dry-run --from-file comics.yaml -o yaml

apiVersion: v1
data:
 comics.yaml: |+
 superhero: Doctor Strange
 villain: Thanos

kind: ConfigMap
metadata:
 creationTimestamp: null
 name: file-config

apiVersion: v1
kind: ConfigMap
metadata:
  name: env-config
  namespace: default
data:
  SUPERHERO: Superman
  VILLAIN: Lex Luthor

apiVersion: v1
kind: Pod
metadata:
  name: some-pod
spec:
  containers:
  - name: some-container
    image: busybox
    command: [ "/bin/sh", "-c", "watch 'echo \"superhero: $SUPERHERO villain: $VILLAIN\"'" ]
    envFrom:
    - configMapRef:
        name: env-config
  restartPolicy: Never

$ kubectl create -f env-config.yaml
configmap "env-config" created

$ kubectl create -f some-pod.yaml
pod "some-pod" created

$ kubectl logs -f some-pod

Every 2s: echo "superhero: $SUPERHERO villain: $VILLAIN"      2019-02-08 20:50:39

superhero: Superman villain: Lex Luthor

$ kubectl edit configmap env-config

# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
data:
 SUPERHERO: Batman
 VILLAIN: Joker
kind: ConfigMap
metadata:
 creationTimestamp: 2019-02-08T20:49:37Z
 name: env-config
 namespace: default
 resourceVersion: "874765"
 selfLink: /api/v1/namespaces/default/configmaps/env-config
 uid: 0c83dee5-2be3-11e9-9999-0800275914a6

configmap "env-config" edited

$ kubectl get configmap env-config -o yaml

apiVersion: v1
data:
 SUPERHERO: Batman
 VILLAIN: Joker
kind: ConfigMap
metadata:
 creationTimestamp: 2019-02-08T20:49:37Z
 name: env-config
 namespace: default
 resourceVersion: "875323"
 selfLink: /api/v1/namespaces/default/configmaps/env-config
 uid: 0c83dee5-2be3-11e9-9999-0800275914a6

$ kubectl logs -f some-pod

Every 2s: echo "superhero: $SUPERHERO villain: $VILLAIN"    2019-02-08 20:59:22

superhero: Superman villain: Lex Luthor

$ kubectl delete -f some-pod.yaml
pod "some-pod" deleted

$ kubectl create -f some-pod.yaml
pod "some-pod" created

$ kubectl logs -f some-pod

Every 2s: echo "superhero: $SUPERHERO villain: $VILLAIN" 2019-02-08 21:45:47

superhero: Batman villain: Joker

apiVersion: v1
kind: Pod
metadata:
  name: some-other-pod
spec:
  containers:
  - name: some-container
    image: busybox
    command: [ "/bin/sh", "-c", "watch \"cat /etc/config/comics\"" ]
    volumeMounts:
    - name: config-volume
      mountPath: /etc/config
  volumes:
  - name: config-volume
    configMap:
      name: file-config
  restartPolicy: Never

apiVersion: v1
kind: ConfigMap
metadata:
  name: file-config
  namespace: default
data:
  comics: |+
    superhero: Doctor Strange
    villain: Thanos

$ kubectl create -f file-config.yaml
configmap "file-config" created

$ kubectl create -f some-other-pod.yaml
pod "some-other-pod" created

$ kubectl logs -f some-other-pod

Every 2s: cat /etc/config/comics      2019-02-08 22:15:08

superhero: Doctor Strange
villain: Thanos

$ kubectl apply -f file-config.yaml
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
configmap "file-config" configured

$ kubectl get configmap file-config -o yaml
apiVersion: v1
data:
 comics: |+
 superhero: Super Woman
 villain: Medusa

kind: ConfigMap
metadata:
 annotations:
 kubectl.kubernetes.io/last-applied-configuration: |
 {"apiVersion":"v1","data":{"comics":"superhero: Super Woman\nvillain: Medusa\n\n"},"kind":"ConfigMap","metadata":{"annotations":{},"name":"file-config","namespace":"default"}}
 creationTimestamp: 2019-02-08T22:14:01Z
 name: file-config
 namespace: default
 resourceVersion: "881662"
 selfLink: /api/v1/namespaces/default/configmaps/file-config
 uid: d6e892f4-2bee-11e9-9999-0800275914a6

$ kubectl logs -f some-other-pod

Every 2s: cat /etc/config/comics     2019-02-08 23:02:58

superhero: Super Woman
villain: Medusa

apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
  # name must match the spec fields below, and be in the form: <plural>.<group>
  name: superheros.example.org
spec:
  # group name to use for REST API: /apis/<group>/<version>
  group: example.org
  # list of versions supported by this CustomResourceDefinition
  versions:
  - name: v1
    # Each version can be enabled/disabled by Served flag.
    served: true
    # One and only one version must be marked as the storage version.
    storage: true
  # either Namespaced or Cluster
  scope: Cluster
  names:
    # plural name to be used in the URL: /apis/<group>/<version>/<plural>
    plural: superheros
    # singular name to be used as an alias on the CLI and for display
    singular: superhero
    # kind is normally the CamelCased singular type. Your resource manifests use this.
    kind: SuperHero
    # shortNames allow shorter string to match your resource on the CLI
    shortNames:
    - hr

apiVersion: "example.org/v1"
kind: SuperHero
metadata:
  name: antman
spec:
  superpower: "can shrink"
  size: "tiny"

apiVersion: "example.org/v1"
kind: SuperHero
metadata:
  name: hulk
spec:
  superpower: "super strong"
  size: "big"
  color: "green"

$ kubectl create -f superheros-crd.yaml
customresourcedefinition.apiextensions.k8s.io "superheros.example.org" created

$ kubectl create -f antman.yaml
superhero.example.org "antman" created

$ kubectl create -f hulk.yaml
superhero.example.org "hulk" created

$ kubectl get hr
NAME               AGE
antman              5m
hulk                5m

$ kubectl get superhero hulk -o yaml
apiVersion: example.org/v1
kind: SuperHero
metadata:
 creationTimestamp: 2019-02-09T09:58:32Z
 generation: 1
 name: hulk
 namespace: default
 resourceVersion: "932374"
 selfLink: /apis/example.org/v1/namespaces/default/superheros/hulk
 uid: 4256d27b-2c51-11e9-9999-0800275914a6
spec:
 color: green
 size: big
 superpower: super strong

$ kubectl get crd -n argocd
NAME                         AGE
applications.argoproj.io     20d
appprojects.argoproj.io      20d

$ kubectl get endpoints
NAME                   ENDPOINTS             AGE
kubernetes             192.168.99.122:8443   27d
link-db                172.17.0.13:5432      16d
link-manager           172.17.0.10:8080      16d
social-graph-db        172.17.0.8:5432       26d
social-graph-manager   172.17.0.7:9090       19d
user-db                172.17.0.12:5432      18d
user-manager           172.17.0.9:7070       18d