code: function identifyGlobals (row, i, rows) {
    var ast = row[kAst]
    var globalScope = ast.parent
  
    var scope = scan.scope(ast)
    if (scope) {
      scan.scope(globalScope).getUndeclaredNames().forEach(function (name) {
        rows.usedGlobalVariables.add(name)
      })
    }
  }
docs: Collect all global variables that are used in any module. This is done separately from the next step (markDuplicateVariableNames) so that global variables used in "later" modules, when colliding with a module variable name in an "earlier" module, are correctly deduped. See https://github.com/browserify/tinyify/issues/10