docs: function eatCharacter(stream) {
          var first = stream.next();
          // Read special literals: backspace, newline, space, return.
          // Just read all lowercase letters.
          if (first.match(/[a-z]/) && stream.match(/[a-z]+/, true)) {
              return;
          }
          // Read unicode character: \u1000 \uA0a1
          if (first === "u") {
              stream.match(/[0-9a-z]{4}/i, true);
          }
      }