FirstLineOfCode:

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   Return the first line of code for a m-file. This is the first line that
   has characters but does not begin with a comment. If no lines are found,
   empty '' is returned.
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   Form:
   line = FirstLineOfCode( filename );
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   ------
   Inputs
   ------
   fileName     (1,:)     File name

   -------
   Outputs
   -------
   line         (1,:)     First line of code

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