<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _interpolate(start, end, step, total_steps):
 """ Interpolate a value from start to end at a given progress. :param start: The start value. :param end: The end value. :param step: The current step. :param total_steps: The total number of steps. :return: The interpolated value at the given progress. """

        diff = end - start
        progress = step / (total_steps - 1)
        return start + progress * diff