fluent assertion "vector<token> should be empty"
fluent assertion for "vector<token> should equal {set}"
derive a class to shorten the syntax for describing a root node in the tests
derive a class to shorten the syntax for describing a named node in the tests
derive a class to shorten the syntax for describing an edge name in the tests
derive a class to shorten the syntax for describing a horizontal edge in the tests
derive a class to shorten the syntax for describing an ascending edge part in the tests
derive a class to shorten the syntax for describing an descending edge part in the tests
derive a class to shorten the syntax for describing an vertical edge part in the tests
move derived token classes into product code