Return false instead of null for boolean attributes

src/GeoIp2/Model/AbstractModel.php

@@ -23,7 +23,15 @@ abstract class AbstractModel implements \JsonSerializable
      */
     protected function get($field)
     {
-        return isset($this->raw[$field]) ? $this->raw[$field] : null;
+        if (isset($this->raw[$field])) {
+            return $this->raw[$field];
+        } else {
+            if (preg_match('/^is_/', $field)) {
+                return false;
+            } else {
+                return null;
+            }
+        }
     }
 
     /**

src/GeoIp2/Record/AbstractRecord.php

@@ -25,7 +25,11 @@ abstract class AbstractRecord implements \JsonSerializable
         if ($this->__isset($attr)) {
             return $this->record[$key];
         } elseif ($this->validAttribute($attr)) {
-            return null;
+            if (preg_match('/^is_/', $key)) {
+                return false;
+            } else {
+                return null;
+            }
         } else {
             throw new \RuntimeException("Unknown attribute: $attr");
         }