code: def load(self,filename):
          
          assert os.path.exists(filename), "couldn't find control file {0}".format(filename)
          f = open(filename, 'r')
  
          while True:
              line = f.readline()
              if line == "":
                  raise Exception("Pst.load() error: EOF when trying to find first line - #sad")
              if line.strip().split()[0].lower() == "pcf":
                  break
          assert line.startswith("pcf"), "Pst.load() error: first noncomment line must start with 'pcf', not '{0}'".format(line)
          raw = line.strip().split()
  
          if len(raw) > 1 and "version" in raw[1].lower():
              raw = raw[1].split('=')
              if len(raw) > 1:
                  try:
                      self._version = int(raw[1])
                  except:
                      pass
          if self._version == 1:
              self._load_version1(filename)
          elif self._version == 2:
              self._load_version2(filename)
          else:
              raise Exception("Pst.load() error: version must be 1 or 2, not '{0}'".format(version))
docs: entry point load the pest control file.  sniffs the first non-comment line to detect the version (if present)
  
          Parameters
          ----------
          filename : str
              pst filename
  
          Raises
          ------
              lots of exceptions for incorrect format