code: def platform_default():
      
      osname = os.name
      if osname == 'java':
          osname = os._osType
      if osname == 'posix':
          if sys.platform == 'cygwin':
              return 'cygwin'
          elif sys.platform.find('irix') != -1:
              return 'irix'
          elif sys.platform.find('sunos') != -1:
              return 'sunos'
          elif sys.platform.find('hp-ux') != -1:
              return 'hpux'
          elif sys.platform.find('aix') != -1:
              return 'aix'
          elif sys.platform.find('darwin') != -1:
              return 'darwin'
          else:
              return 'posix'
      elif os.name == 'os2':
          return 'os2'
      else:
          return sys.platform
docs: Return the platform string for our execution environment.
  
      The returned value should map to one of the SCons/Platform/*.py
      files.  Since we're architecture independent, though, we don't
      care about the machine architecture.