depth_first_rewrite_expr: Transform an expression.
In mailund/foolbox: Function Manipulation Toolbox

Traverses the expression expr depth-first and transform it using callbacks.

1 2	depth_first_rewrite_expr(expr, callbacks, params = list(), topdown = list(), wflags = warning_flags(), ...)

`expr`	An R expression
`callbacks`	List of callbacks to apply.
`params`	Parameters of the function we are rewriting. If we are working on a raw expression, just use the default, which is an empty list.
`topdown`	A list of additional information gathered in the traversal.
`wflags`	Warning flags, see `warning_flags()`.
`...`	Additional data that will be passed along to callbacks.