Recursive Function to find substrings in a possibly multidimentional array

I needed this, and was happy enough with the results to share it.

This is like PHP in_array, but it searches for a substring.
for a one-dimensional array, it returns the key of the first match.
For a multi-dimensional array, it returns a csv list of keys to the first match.

<?php
function substr_in_array ($array, $term, $case=true )
{
//optional third argument set to false will cause case insensitive test.
// return false if the provide $array is not actually an array.
if(!is_array($array))
  {
    //echo 'Not Array';
    return false;
  }
// if $case has been set to false, make the term and each value lower case.
if(!$case)
  {
   $term=strtolower($term);
  }
    foreach ( $array as $key => $value )
    {
      if(is_array($value))
        {
           $inner=substr_in_array($value,$term,$case);
           if ($inner!==false){return $key.','.$inner;}
        }
      else
        {
        if(!$case)
          {
         $value=strtolower($value);
       }
     echo 'Actually doing the text  comparison now: is '.$term.' in '.$value.'?
'."\n";
     // if the term is found in the value, return the $key.
        if (strpos($value, $term ) !== false )
          {
            return $key;
          }
        }
    }
    return false;
}
?>