Map over esprima nodes conveniently.
npm install esmap
Maps over the given node's children with the given function. Returns a fresh node.
If a node has a property with an array of children, fn(child, key, node) is called for every child as if they were direct descendants, but the truthy return values are Array#concat'd together.
A falsy value is ignored (the node is removed from the array), an array value is concatenated, a non-array value is placed into the array.