Zephir\Variable::setIsExternal PHP Method

    public function setIsExternal($isExternal)
    {
        $this->isExternal = $isExternal;
        $this->variantInits = 1;
    }

 /**
  * Return a variable in the symbol table, it will be used for a mutating operation
  * This method implies mutation of one of the members of the variable but no the variables it self
  *
  * @param string $name
  * @param CompilationContext $compilationContext
  * @param array $statement
  * @return Variable
  */
 public function getVariableForUpdate($name, CompilationContext $compilationContext, array $statement = null)
 {
     /**
      * Create superglobals just in time
      */
     if ($this->isSuperGlobal($name)) {
         if (!$this->hasVariable($name)) {
             /**
              * @TODO, injecting globals, initialize to null and check first?
              */
             $superVar = new Variable('variable', $name, $compilationContext->currentBranch);
             $superVar->setIsInitialized(true, $compilationContext, $statement);
             $superVar->setDynamicTypes('array');
             $superVar->increaseMutates();
             $superVar->increaseUses();
             $superVar->setIsExternal(true);
             $superVar->setUsed(true, $statement);
             $this->variables[$name] = $superVar;
             return $superVar;
         }
     }
     if (!$this->hasVariable($name)) {
         throw new CompilerException("Cannot mutate variable '" . $name . "' because it wasn't defined", $statement);
     }
     $variable = $this->getVariable($name);
     $variable->increaseUses();
     $variable->increaseMutates();
     /**
      * Saves the last place where the variable was mutated
      * We discard mutations inside loops because iterations could use the value
      * and Zephir only provides top-down compilation
      */
     $variable->setUsed(true, $statement);
     return $variable;
 }