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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_sites_in_sphere(self, pt, r):
 """ Find all sites within a sphere from a point. Args: pt (3x1 array):
 Cartesian coordinates of center of sphere. r (float):
 Radius of sphere. Returns: requires the distance. """

        neighbors = []
        for site in self._sites:
            dist = site.distance_from_point(pt)
            if dist <= r:
                neighbors.append((site, dist))
        return neighbors