title: How to know what a function takes as parameter what does it return after adding a DLL file
body: <p>I'm working on Web API C#, So one of my colleague have implemented a function
  that do some calculation that I need to use as well.</p>
  <p>He will share my the DLL file for that. I know I need to add the DLL in my project
  but how can I know exactly what functions are available in that DLL file
  ,their names , their input parameter and output parameter?</p>