add environment struct

       *elem_config,

       doc->data,

       *doc,

       doc->env,

       &elem);

   if (!rc) {

  Document();

  Measure width;

  Measure height;

  Environment env;

  ColorScheme color_scheme;

  Color background_color;

  Color text_color;

#include <functional>

#include "plist/plist.h"

#include "utils/return_code.h"

#include "environment.h"

namespace plotfx {

struct Layer;

struct Rectangle;

struct Document;

struct DataContext;

struct Environment;

using plist::PropertyList;

    const plist::PropertyList&,

    const DataContext&,

    const Document&,

    const Environment&,

    T*)>;

struct Element {

    const plist::PropertyList& plist,

    const DataContext& ctx,

    const Document& doc,

    const Environment& env,

    ElementRef* elem) {

  const auto& elem_entry = elems.find(name);

  if (elem_entry == elems.end()) {

    return ReturnCode::errorf("NOTFOUND", "no such element: $0", name);

  }

  return elem_entry->second(plist, ctx, doc, elem);

  return elem_entry->second(plist, ctx, doc, env, elem);

}

} // namespace plotfx

namespace plotfx {

struct Document;

struct Environment;

using ElementBuilder = std::function<ReturnCode (

    const plist::PropertyList&,

    const DataContext&,

    const Document&,

    const Environment&,

    ElementRef* elem)>;

template <typename T>

    const plist::PropertyList& plist,

    const DataContext& ctx,

    const Document& doc,

    const Environment& env,

    ElementRef* elem);

} // namespace plotfx