code: def get_hostname_prefix():
    
    parts = []
  
    # Check if this is the default version
    version = modules.get_current_version_name()
    default_version = modules.get_default_version()
    if version != default_version:
      parts.append(version)
  
    # Check if this is the default module
    module = modules.get_current_module_name()
    if module != 'default':
      parts.append(module)
  
    # If there is anything to prepend, add an extra blank entry for the trailing
    # -dot-
    if parts:
      parts.append('')
  
    return '-dot-'.join(parts)
docs: Returns the hostname prefix of a running Endpoints service.
  
    The prefix is the portion of the hostname that comes before the API name.
    For example, if a non-default version and a non-default service are in use,
    the returned result would be '{VERSION}-dot-{SERVICE}-'.
  
    Returns:
      str, the hostname prefix.