code: def _root_domain():
      
  
      if not hasattr(env,'root_domain'):
          cwd = os.getcwd().split(os.sep)
          domain = ''
          #if the first env.host has a domain name then we'll use that
          #since there are no top level domains that have numbers in them we can test env.host
  
          username, host, port = normalize(env.hosts[0])
          if host[-1] in string.ascii_letters:
              domain_parts = env.host.split('.')
              length = len(domain_parts)
              if length==2:
                  #assumes .com .net etc so we want the full hostname for the domain
                  domain = host
              elif length==3 and len(domain_parts[-1])==2:
                  #assume country tld so we want the full hostname for domain
                  domain = host
              elif length >=3:
                  #assume the first part is the hostname of the machine
                  domain = '.'.join(domain[1:])
          #we'll just pick the first directory in the path which has a period.
          else:
              for d in cwd:
                  if '.' in d: 
                      domain = d
          if not domain and env.INTERACTIVE:
              domain = prompt('Enter the root domain for this project ',default='example.com')
          else:
              domain = 'example.com'
          env.root_domain = domain
      return env.root_domain
docs: Deduce the root domain name - usually a 'naked' domain.
      
      This only needs to be done prior to the first deployment