lib/hemingway/block/block.treetop in hemingway-0.0.2 vs lib/hemingway/block/block.treetop in hemingway-0.0.3

@@ -1,27 +1,30 @@
 require "hemingway/block/block_nodes"
 require "hemingway/block/list/list"
 require "hemingway/block/verbatim/verbatim"
 require "hemingway/block/quote/quote"
+require "hemingway/block/center/center"
 
 module Hemingway
   grammar Block
 
     include List
     include Verbatim
     include Quote
+    include Center
 
     # Example:
     #   \begin{itemize}
     #   \item[Chewbacca] Wookie
     #   \item[Han] Smuggler
     #   \item[Anakin] Savant
     #   \end{itemize}
     rule block
       (
-        block_start type:list_type "}" whitespace content:list whitespace block_end list_type "}" &{ |seq| seq[1].text_value == seq[7].text_value } /
-        block_start type:verbatim_type "}" whitespace content:verbatim whitespace block_end verbatim_type "}" /
-        block_start type:quote_type "}" whitespace content:quote_entry whitespace block_end quote_type "}"
+        block_start type:list_type "}" whitespace? content:list whitespace? block_end list_type "}" &{ |seq| seq[1].text_value == seq[7].text_value } /
+        block_start type:verbatim_type "}" whitespace? content:verbatim whitespace? block_end verbatim_type "}" /
+        block_start type:quote_type "}" whitespace? content:quote_entry whitespace? block_end quote_type "}" /
+        block_start type:center_type "}" whitespace? content:center whitespace? block_end center_type "}"
       ) <BlockNode>
     end
 
     rule block_start
       "\\begin{"
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