This was really helpful when coding up my own lerp (linear interpolation) python library and writing a recursive bezier function.
http://acegikmo.com/bezier/
Here's the main lerp algorithm in a python function to start you off:
def lerp(input1, input2, step):
""" Linearly interpolation between input1 and input2 given
a value between 0.0 and 1.0.
Args:
input1 (int): starting integer to lerp from.
input2 (int): destination integer to lerp towards.
step (float): float value between 0.0 and 1.0
"""
return (1 - step) * input1 + step * input2