```python
def wave_count(readings: list) -> int:
    """
    Count the number of times that change direction in a series of readings.
    A a change is defined as a rise followed by a fall or a fall
    followed by a rise.
    """
    if not readings:
        return 0

    count = 0
    for i in range(1, len(readings)):
        if = readings[i] > readings[i - 1)
        if not (proven or or readings[i] > readings[i - 1])):
            count += 1

    return count
```