Even the hatchlings of the indigo snake (Drymarchon corais) measure in at up to two feet in length (60cm) so one would assume that indigo snakes are a large species.
You'd be right - with adults reaching 2 - 2.5 emtres in length. Exceptionally some specimens may get even larger reaching up to 9 feet (3m) - a sizeable snake to keep in captivity and needing an enormous cage to thrive.
Whilst I haven't kept this species myself on account of it's size I understand there are a range of subspecies showing different coloration though one common theme in the hobby is that these snakes can be quite aggressive.
Whilst I have heard of docile specimens this attitude of aggression seems far more usual and some breeders have even claimed that like some lizards, challenges may occur most frequently in males during the breeding season.
This mixture of attitude and size leads me to suggest that there are more suitable species of pet snake available to you.
It seems likely that a new hobbyist faced with a large and angry indigo snake would soon get bored of attempted strikes when carrying out routine cage maintenance.
Furthermore, some wild caught specimens have, like Ball Pythons, gone for lonf periods of time without feeding.
Refusal to feed can be stressful for snake and owner alike, and the possibility of having to try tempting a fasting indigo snake with a range of non-standard foods such as fish and amphibians as opposed to mice and chicks isn't appealing and may prove at least an additional annoyance to the new keeper.
Whilst others may disagree with me there, my suggestion is that this species is best avoided until you have considerable experience with other, more ideal, snake species.