class SyntaxTree::PrettyPrintVisitor

def visit_binary(node)

before we print it out.
This is here because we need to make sure the operator is cast to a string 
def visit_binary(node)
  node(node, "binary") do
    field("left", node.left)
    text("operator", node.operator.to_s)
    field("right", node.right)
    comments(node)
  end
end