# Nucleotide Count

Welcome to Nucleotide Count on Exercism's Perl 5 Track.
If you need help running the tests or submitting your code, check out `HELP.md`.

## Instructions

Each of us inherits from our biological parents a set of chemical instructions known as DNA that influence how our bodies are constructed. All known life depends on DNA!

> Note: You do not need to understand anything about nucleotides or DNA to complete this exercise.

DNA is a long chain of other chemicals and the most important are the four nucleotides, adenine, cytosine, guanine and thymine. A single DNA chain can contain billions of these four nucleotides and the order in which they occur is important!
We call the order of these nucleotides in a bit of DNA a "DNA sequence".

We represent a DNA sequence as an ordered collection of these four nucleotides and a common way to do that is with a string of characters such as "ATTACG" for a DNA sequence of 6 nucleotides.
'A' for adenine, 'C' for cytosine, 'G' for guanine, and 'T' for thymine.

Given a string representing a DNA sequence, count how many of each nucleotide is present.
If the string contains characters that aren't A, C, G, or T then it is invalid and you should signal an error.

For example:

```
"GATTACA" -> 'A': 3, 'C': 1, 'G': 1, 'T': 2
"INVALID" -> error
```

## Source

### Created by

- @bentglasstube

### Contributed to by

- @kytrinyx
- @m-dango
- @rfilipo

### Based on

The Calculating DNA Nucleotides_problem at Rosalind - http://rosalind.info/problems/dna/