code: function appendTypeParameters(typeParameters, declarations) {
              for (var _i = 0, declarations_2 = declarations; _i < declarations_2.length; _i++) {
                  var declaration = declarations_2[_i];
                  var tp = getDeclaredTypeOfTypeParameter(getSymbolOfNode(declaration));
                  if (!typeParameters) {
                      typeParameters = [tp];
                  }
                  else if (!ts.contains(typeParameters, tp)) {
                      typeParameters.push(tp);
                  }
              }
              return typeParameters;
          }
docs: Appends the type parameters given by a list of declarations to a set of type parameters and returns the resulting set. The function allocates a new array if the input type parameter set is undefined, but otherwise it modifies the set in-place and returns the same array.