isCallable() public method

Is this parameter a callable?
public isCallable ( ) : boolean
return boolean
 private function assertSameParameterAttributes(\ReflectionParameter $original, ReflectionParameter $stubbed)
 {
     $this->assertSame($original->getName(), $stubbed->getName());
     $this->assertSame($original->isArray(), $stubbed->isArray());
     $this->assertSame($original->isCallable(), $stubbed->isCallable());
     //$this->assertSame($original->allowsNull(), $stubbed->allowsNull()); @TODO WTF?
     $this->assertSame($original->canBePassedByValue(), $stubbed->canBePassedByValue());
     $this->assertSame($original->isOptional(), $stubbed->isOptional());
     $this->assertSame($original->isPassedByReference(), $stubbed->isPassedByReference());
     $this->assertSame($original->isVariadic(), $stubbed->isVariadic());
     if ($class = $original->getClass()) {
         $stubbedClass = $stubbed->getClass();
         $this->assertInstanceOf(ReflectionClass::class, $stubbedClass);
         $this->assertSame($class->getName(), $stubbedClass->getName());
     } else {
         $this->assertNull($stubbed->getClass());
     }
 }
 /**
  * {@inheritDoc}
  */
 public function isCallable()
 {
     return $this->betterReflectionParameter->isCallable();
 }