Understanding namespaces I am new to namespaces and I am practicing with Drupal 8. I have created a custom module and have installed the contrib, devel.
Inside my module, I have defined a block.
namespace Drupal\twitter_pull\Plugin\Block;
use Drupal\block\BlockBase;

/**
 * Provides a block for executing PHP code.
 *
 * @Block(
 *   id = &quot;twitter_pull_tweets_block&quot;,
 *   admin_label = @Translation(&quot;Twitter Tweets&quot;)
 * )
 */
class TweetsBlock extends BlockBase {

  /**
   * Builds and returns the renderable array for this block plugin.
   *
   * @return array
   *   A renderable array representing the content of the block.
   *
   * @see \Drupal\block\BlockViewBuilder
   */
  public function build() {
    dpm(array('this','is','a','test'));
    return 'this is a block';
  }
}

It works fine. Why do I have access to the devel functions? Where in my code do I include the namespace for devel that I should have access to dpm()?
Straight from the PHP Global space docs:


  Without any namespace definition, all class and function definitions are placed into the global space - as it was in PHP before namespaces were supported. Prefixing a name with \ will specify that the name is required from the global space even in the context of the namespace.


Devel's dpm() is declared in 'Global space', and since there's no other dpm() function declared in your namespace, the 'global' one is used (no need for the preceeding \).