code: def init_env():
      
      env.ROLES_DIR = ROLE_DIR
      env.services = []
      env.confirm_deployment = False
      env.is_local = None
      env.base_config_dir = '.'
      env.src_dir = 'src' # The path relative to fab where the code resides.
      env.sites = {} # {site:site_settings}
      env[SITE] = None
      env[ROLE] = None
  
      env.hosts_retriever = None
      env.hosts_retrievers = type(env)() #'default':lambda hostname: hostname,
  
      env.hostname_translator = 'default'
      env.hostname_translators = type(env)()
      env.hostname_translators.default = lambda hostname: hostname
  
      env.default_site = None
  
      # A list of all site names that should be available on the current host.
      env.available_sites = []
  
      # A list of all site names per host.
      # {hostname: [sites]}
      # If no entry found, will use available_sites.
      env.available_sites_by_host = {}
  
      # The command run to determine the percent of disk usage.
      env.disk_usage_command = "df -H | grep -vE '^Filesystem|tmpfs|cdrom|none' | awk '{print $5 " " $1}'"
  
      env.burlap_data_dir = '.burlap'
  
      env.setdefault('roledefs', {})
      env.setdefault('roles', [])
      env.setdefault('hosts', [])
      env.setdefault('exclude_hosts', [])
docs: Populates the global env variables with custom default settings.