@Nullable
    static Assignment create(@NotNull PsiAssignmentExpression assignment) {
      PsiExpression rhs = assignment.getRExpression();
      if (rhs == null) return null;
      PsiReference reference = tryCast(assignment.getLExpression(), PsiReference.class);
      if (reference == null) return null;
      PsiVariable lhs = tryCast(reference.resolve(), PsiVariable.class);
      return lhs == null ? null : new Assignment(lhs, rhs);
    }
@Nullable
    static Assignment create(@NotNull PsiAssignmentExpression assignment)