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MyFunComplex[x_, y_] := Module[{u}, u = MyFunSimple[x, y]; 
      If[u == 0, Print["Sin(x+y)=0"], Print["Sin(x+y)!=0"]]; ]
 
MyFunSimple[x_, y_] := Sin[x + y]
 
AnotherMyFunComplex[x_] := Module[{u}, u = x + 3; Sin[u]]