angular 2 typescript An implementation cannot be declared in ambient contexts

Question

I am new to typescript and I am trying to create a function for an angular 2 directive. Can anyone explain, in language for n00bs, what the error is trying to tell me when I

Answer 1

I think this happened to me, because I accidentally edited one of the files in node_modules. This fixed it for me:

rm -r node_modules
npm install