How to use the pixiedust.utils.shellAccess.ShellAccess.npm function in pixiedust

def __init__(self, shell, node):
        super(PixiedustNodeMagics,self).__init__(shell=shell) 
        display(HTML(
"""
            <div style="margin:10px"> 
            <a href="https://github.com/pixiedust/pixiedust_node"> 
            <img style="float:left;margin-right:10px" src="https://github.com/pixiedust/pixiedust_node/raw/master/docs/_images/pdn_icon32.png"> 
            </a> 
            <span>Pixiedust Node.js</span> 
            </div> 
"""
        ))
        self.n = node
        ShellAccess.npm = Npm()
        ShellAccess.node = self.n