--description--

Given a string in camel case, return the snake case version of the string using the following rules:

• The input string will contain only letters (A-Z and a-z) and will always start with a lowercase letter.
• Every uppercase letter in the camel case string starts a new word.
• Convert all letters to lowercase.
• Separate words with an underscore (_).

--hints--

to_snake("helloWorld") should return "hello_world".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(to_snake("helloWorld"), "hello_world")`)
}})

to_snake("myVariableName") should return "my_variable_name".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(to_snake("myVariableName"), "my_variable_name")`)
}})

to_snake("freecodecampDailyChallenges") should return "freecodecamp_daily_challenges".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(to_snake("freecodecampDailyChallenges"), "freecodecamp_daily_challenges")`)
}})

--seed--

--seed-contents--

def to_snake(camel):

    return camel

--solutions--

import re
def to_snake(camel):
    return re.sub(r'([A-Z])', r'_\1', camel).lower()