config: EOL mapping mapping-body list EOL
config   ::= EOL* ( mapping | mapping-body | list ) EOL*
 no referencesmapping: ( mapping-body }
mapping  ::= '(' mapping-body '}'
 referenced by: config value list: [ list-body ]
list     ::= '[' list-body ']'
 referenced by: config value mapping-body: EOL key_value EOL
         ::= ( EOL* key_value EOL* )*
 referenced by: config mapping key_value: key : = EOL value , EOL
         ::= key ( ':' | '=' ) EOL* value ( ',' | EOL )?
 referenced by: mapping-body key: strings IDENTIFIER
key      ::= strings
           | IDENTIFIER
 referenced by: key_value strings: STRING
strings  ::= STRING+
 referenced by: key value list-body: EOL value , EOL EOL
         ::= ( EOL* value ( ',' | EOL )? EOL* )*
 referenced by: list value: mapping list strings IDENTIFIER INTEGER FLOAT COMPLEX true false null
value    ::= mapping
           | list
           | strings
           | IDENTIFIER
           | INTEGER
           | FLOAT
           | COMPLEX
           | 'true'
           | 'false'
           | 'null'
 referenced by: key_value list-body