src/workers/parser/mapBindings.js
function globalizeAssignment(node, bindings) {
  return t.assignmentExpression(
    node.operator,
    getAssignmentTarget(node.left, bindings),
    node.right
  );
}
function globalizeAssignment(node, bindings) {
  return t.assignmentExpression(
    node.operator,
    getAssignmentTarget(node.left, bindings),
    node.right
  );
}
function globalizeAssignment ( node , bindings ) { return t . assignmentExpression ( node . operator , getAssignmentTarget ( node . left , bindings ) , node . right ) ; }
translates new bindings `a = 3` into `self.a = 3` and keeps assignments the same for existing bindings.
translates new bindings a = 3 into self . a = 3 and keeps assignments the same for existing bindings .