SKISTK    SKISTK    SKISTK    SKISTK    SKISTK    SKISTK    SKISTK    
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                              ******

SUBROUTINE SKISTK (IR, ISKWRK, ISTFL)
Returns an integer flag to indicate whether reaction IR uses
sticking coefficients.

INPUT
IR        - Integer scalar, index of a surface reaction.
ISKWRK(*) - Integer workspace array; dimension at least LENISK.

OUTPUT
ISTFL     - Integer scalar,
            0, reaction IR does not use sticking coefficients
            1, reaction IR does use sticking coefficients