Implement support for built-in python functions on the kernel

[1e-to]

Built-in functions

• [x] abs()
• [ ] bool
• [ ] complex
• [ ] enumerate()
• [x] float
• [x] int
• [x] len()
• [ ] min()
• [ ] max()
• [x] range (only ints/uints)
• [x] round()
• [ ] zip()