(Program
  (SubscriptAccess
    { (Identifier) -> (Identifier) }
    { (StringLiteral) -> (Identifier) })
  (SubscriptAccess
    { (Identifier) -> (Identifier) }
    { (SymbolLiteral) -> (SymbolLiteral) })
{+(Assignment
    (SubscriptAccess
      (Identifier)
      (Identifier))
    (IntegerLiteral))+})