old_contents: import os
  import numpy as np
  import bz2
  data_dir = os.path.expanduser("~/.ipyvolume/datasets")
  if not os.path.exists(data_dir):
  	os.makedirs(data_dir)
  
  
  class Dataset(object):
  	def __init__(self, name):
  		self.name = name
  		self.url = "https://github.com/maartenbreddels/ipyvolume/raw/master/datasets/%s.npy.bz2" % name
  		self.path = os.path.join(data_dir, name+".npy.bz2")
  
  	def download(self, force=False):
  		if not os.path.exists(self.path) or force:
  			print("Downloading %s to %s" % (self.url, self.path))
  			code = os.system(self.wget_command())
  
  	def fetch(self):
  		self.download()
  		if os.path.exists(self.path):
  			f = bz2.BZ2File(self.path)
  			self.data = np.load(f)
  		else:
  			raise Exception("file not found and/or download failed")
  		return self
  
  	def wget_command(self):
  		return "wget --progress=bar:force -c -P %s %s" % (data_dir, self.url)
  
  hdz2000 = Dataset("hdz2000")
  aquariusA2 =  Dataset("aquarius-A2")
new_contents: import os
  import numpy as np
  import bz2
  data_dir = os.path.expanduser("~/.ipyvolume/datasets")
  if not os.path.exists(data_dir):
  	os.makedirs(data_dir)
  
  
  class Dataset(object):
  	def __init__(self, name):
  		self.name = name
  		self.url = "https://github.com/maartenbreddels/ipyvolume/raw/master/datasets/%s.npy.bz2" % name
  		self.path = os.path.join(data_dir, name+".npy.bz2")
  
  	def download(self, force=False):
  		if not os.path.exists(self.path) or force:
  			print("Downloading %s to %s" % (self.url, self.path))
  			code = os.system(self.wget_command())
  
  	def fetch(self):
  		self.download()
  		if os.path.exists(self.path):
  			f = bz2.BZ2File(self.path)
  			self.data = np.load(f)
  		else:
  			raise Exception("file not found and/or download failed")
  		return self
  
  	def wget_command(self):
  		return "cd %s; curl -O -L %s" % (data_dir, self.url)
  		#return "wget --progress=bar:force -c -P %s %s" % (data_dir, self.url)
  
  hdz2000 = Dataset("hdz2000")
  aquariusA2 =  Dataset("aquarius-A2")
subject: use curl instead of wget