From the link you provided:

Sample a sequence of characters according to a sequence of probability distributions output of the RNN

Arguments: parameters -- python dictionary containing the parameters Waa, Wax, Wya, by, and b. char_to_ix -- python dictionary mapping each character to an index.

Returns: indices -- a list of length n containing the indices of the sampled characters

You are returning the indices from a dictionary you gave as argument. Why should you use char_to_integer indices

From the link you provided:

Sample a sequence of characters according to a sequence of probability distributions output of the RNN

Arguments: parameters -- python dictionary containing the parameters Waa, Wax, Wya, by, and b. char_to_ix -- python dictionary mapping each character to an index.

Returns: indices -- a list of length n containing the indices of the sampled characters

You are returning the indices from a dictionary you gave as argument. Why should you use char_to_integer indices.