title: Get or default function in JQ?
body: <p>Assuming there is a json file:</p>
  
  <pre><code>{
    "columns": {
      "id": {
        "required": true,
        "type": "integer"
      },
      "name": {
        "required": false,
        "type": "string"
      },
      "description": {
        "type": "string"
      }
    }
  }
  </code></pre>
  
  <p>I want to use <code>jq</code> to get the value "required" field for each column. If the field "required" does not exist, it should return the default value <code>false</code>.</p>
  
  <p>Specifically:</p>
  
  <pre><code>jq '.columns.id | getOrDefault("required", false)'  # true
  jq '.columns.name | getOrDefault("required", false)'  # false
  jq '.columns.description | getOrDefault("required", false)'  # false
  </code></pre>
  
  <p>How to implement this magic getOrDefault() function in <code>jq</code>?</p>