These methods control how the value of a given node is printed. New methods can be added if support is needed for a novel class

## Usage

tree_label(x, opts)

## Arguments

x

A tree like object (list, etc.)

opts

A list of options that directly mirrors the named arguments of tree. E.g. list(val_printer = crayon::red) is equivalent to tree(..., val_printer = crayon::red).