title: How to call a python class function from another file
body: <p>I have this class in my parser.py file</p>
  
  <pre><code>class HostInfo(object):
  def __init__(self, host_id):
      self.osclass = []
      self.osmatch = []
      self.osfingerprint = []
      self.portused = []
      self.ports = []
      self.extraports = []
      self.tcpsequence = {}
      self.hostnames = []
      self.tcptssequence = {}
      self.ipidsequence = {}
      self.trace = {'port': '', 'proto': '', 'hop': []}
      self.status = {}
      self.address = []
      self.hostscript = []
  
      # Umit extension
      self.id = host_id
      self.comment = ''
  
      # XXX this structure it not being used yet.
      self.nmap_host = {
              'status': {'state': '', 'reason': ''},
              'smurf': {'responses': ''},
              'times': {'to': '', 'srtt': '', 'rttvar': ''},
              'hostscript': [],
              'distance': {'value': ''},
              'trace': {'port': '', 'proto': '', 'hop': []},
              'address': [],
              'hostnames': [],
              'ports': [],
              'uptime': {'seconds': '', 'lastboot': ''},
              'tcpsequence': {'index': '', 'values': '', 'class': ''},
              'tcptssequence': {'values': '', 'class': ''},
              'ipidsequence': {'values': '', 'class': ''},
              'os': {}
              }
  </code></pre>
  
  <p>after that it defined a function which trying to find an host id from a xml file </p>
  
  <pre><code>def get_id(self):
      try:
          return self._id
      except AttributeError:
          raise Exception("Id is not set yet.")
  
  def set_id(self, host_id):
      try:
          self._id = int(host_id)
      except (TypeError, ValueError):
          raise Exception("Invalid id! It must represent an integer, "
                  "received %r" % host_id)
  </code></pre>
  
  <p>Now i want to use call this <code>get_id</code> function from an another file.I tried so many time but it shows an error i.e. module can't be import</p>