anchor.diff:  
   <non_variable_value_list> ::= '(' <value> ( ',' <value> )* ')'
   
  +<python_style_list> ::= '[' <python_style_value> ( ',' <python_style_value> )* ']'
  +
  +<python_style_dict> ::= '{' <key_value_pair> ( ',' <key_value_pair> )* '}'
  +
  +<python_style_value> ::= <value>
  +                       | <python_style_list>
  +                       | <python_style_dict>
  +
   <value> ::= <numeric>
             | <quoted_string>
             | TRUE
  
positive.code: <route_by_clause> ::= ROUTE BY <quoted_string>
  
  <relevance_model_clause> ::= USING RELEVANCE MODEL <identifier> <prop_list>
                               <relevance_model>
  
  <relevance_model> ::= DEFINED AS <formal_parameters> BEGIN <model_block> END
  
  
negative.code: 
  <prop_list> ::= '(' <key_value_pair> ( ',' <key_value_pair> )* ')'
  
  <key_value_pair> ::= <quoted_string> ':' 
                       ( <value> | <python_style_list> | <python_style_dict> )
  
  <given_clause> ::= GIVEN FACET PARAM <facet_param_list>
  
  