import math


def estimate_risk(entry_price: float, stop_price: float) -> float:
    """
    estimates the risk per share

    :param entry_price: float
    :param stop_price: float
    :return: float
    """
    if math.isnan(entry_price) or math.isnan(stop_price):
        raise TypeError()

    return abs(entry_price - stop_price)