public function test_c()
 {
     $chars = array('<' => '\\3C ', '>' => '\\3E ', '\'' => '\\27 ', '"' => '\\22 ', '&' => '\\26 ', 'Ā' => '\\100 ', ',' => '\\2C ', '.' => '\\2E ', '_' => '\\5F ', 'a' => 'a', 'A' => 'A', 'z' => 'z', 'Z' => 'Z', '0' => '0', '9' => '9', "\r" => '\\D ', "\n" => '\\A ', "\t" => '\\9 ', "" => '\\0 ', ' ' => '\\20 ');
     foreach ($chars as $key => $val) {
         $this->assertEquals($val, Escaper::c($key), 'Failed to escape: ' . $key);
     }
 }