import math


def distance(x1: float, y1: float,
             x2: float, y2: float) -> float:
    """
    Calculate distance from coordinates of two points.

    Parameters
    ----------
    x1, y1 : float
    x2, y2 : float

    Returns
    -------
    float
        Distance of points.
    """

    return math.sqrt(math.pow(x1-x2, 2) + math.pow(y1-y2, 2))