PyPy is a fast, compliant alternative implementation of Python.
 cPython is implemented in C.

 PyPy is implemented in Python.
 What does that mean?

 And how do you test something as huge as an alternative implementation of Python?

Special Guest: Carl Friedrich Bolz-Tereick.

Links:

• PyPy
• How is PyPy Tested? 
• PyPy Speed
• Python Speed Center