Takes the given input and casts all letters to a lower case. The given input must be a valid string.
Converts every letter in a text value to lower case. Use this to normalise values that should always be stored the same way no matter how they arrive, such as email addresses, product codes, or tags, so that “ABC-123” and “abc-123” are treated as the same value later on. Digits, punctuation, and symbols are left untouched; only letters change.