dest_scope {}

# Self is added to dest_scope's env
a +dest_scope {}

# Self is not added anywhere (null_name and or_current=False)
b +dest_scope {null_name}

# Self is added to dest_scope's env (the one of the root list)
c +dest_scope {or_current}

# Self is added to the current env (Self's own)
d +dest_scope {null_name or_current}
