Set/Get the DOS verify flag.
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 Syntax

        GT_Verify([<lNewSetting>]) --> lOldSetting

 Arguments:

      <lNewSetting> is an optional logical parameter. If true (.T.)
      the DOS verify flag will be turned on, if false (.F.) it will be
      turned off. If not passed GT_Verify() just returns the current
      setting.

 Returns:

      The status of the verify flag. If a new setting is passed then
      the previous setting is returned. If a new setting is not
      passed then the current setting is returned.

 Description:

      GT_Verify() can be used to set and get the status of the DOS verify
      flag.

 Examples:

      // Set the DOS verify flag on.

      GT_Verify(TRUE)

      // Display the current DOS verify flag setting.

      ? GT_Verify()

 Source: VERIFY.C

 Author:  Dave Pearson