Letters Only

Check if the given string consists of only letters and spaces and if every letter is in lower case.

Examples

letters_only("PYTHON") ➞ False

letters_only("python") ➞ True

letters_only("12321313") ➞ False

letters_only("i have spaces") ➞ True

letters_only("i have numbers(1-10)") ➞ False

letters_only("") ➞ False

Notes

• Empty arguments will always return False.
• Input values will be mixed (symbols, letters, numbers).