Seychelles Creole sa is generally not classified as a definite article (see Bollée 2004) because it is far from being grammaticalized and used in every instance of a definite reference. But sa shows in some contexts the associative function which is crucial in the definition of definite article in APiCS. As obligatoriness in definite contexts is not a prerequisite for definite-article use, sa must be classified as a definite article here.
Source: Bollée and Rosalie 1994: 224
Source: Michaelis 1994: 184
Source: Bollée 1977: 63