title: Does default_if_none have any use in Django templates?
body: <p>From the Django docs,</p>
  
  <blockquote>
    <p>Generally, if a variable doesn't
    exist, the template system inserts the
    value of the
    TEMPLATE_STRING_IF_INVALID setting,
    which is set to '' (the empty string)
    by default.</p>
    
    <p>Filters that are applied to an invalid
    variable will only be applied if
    TEMPLATE_STRING_IF_INVALID is set to
    '' (the empty string). If
    TEMPLATE_STRING_IF_INVALID is set to
    any other value, variable filters will
    be ignored.</p>
    
    <p>This behavior is slightly different
    for the if, for and regroup template
    tags. If an invalid variable is
    provided to one of these template
    tags, the variable will be interpreted
    as None. Filters are always applied to
    invalid variables within these
    template tags.</p>
  </blockquote>
  
  <p>If an invalid variable always gets translated to '', for template tags and filters other than <em>if</em>, <em>for</em> and <em>regroup</em>, then what good does the template filter <strong>default_if_none</strong> do? Obsolete?</p>