lark/tree.py

shaping. For example, passing "TB" instead of "LR" makes the tree
to be draw vertically instead of horizontally.

https://stackoverflow.com/questions/29003465/pydot-graphviz-how-to-order-horizontally-nodes-in-a-cluster-while-the-rest-of-t

* All exceptions are now under exceptions.py
* UnexpectedInput is now superclass of UnexpectedToken and UnexpectedCharacters,
  all of which support the get_context() and match_examples() methods.

Nearley tool still needs fixing

It emulates antlr's visitor behavior for a dynamic evaluation order of subtrees

When a tuple is passed as the argument to percent-formatting, its
elements are interpreted as multiple arguments. The pretty printer
previously passed tuples (e.g. those introduced via a Transformer) from
the tree directly to the percent operator, causing a TypeError because
the format string only calls for a single argument. This fix simply
wraps the argument in a one-tuple to ensure it is not interpreted as
multiple arguments if it itself is a tuple.

It now knows how to resolve ambiguity! And in a memory-efficient way!