I want to calculate the following limit 

$$L=\lim\_{r \to 0} \left( 1 + r \frac{El^{'}(r)}{El(r)} \right)$$

by letting *Mathematica* to know

$$\lim\_{r \to 0} \frac{El^{'}(r)}{El(r)} = A $$

where $A$ is a constant. It is evident that we should have $L=1$.

I used the following

```
Limit[1 + (r Derivative[1][El][r])/El[r], r -> 0, 
Assumptions -> {Limit[Derivative[1][El][r]/El[r], r -> 0] == a}]

```

But it didn't work.

What should I do?