Lighthouse Labs Yellow Pager example

yellowpager.rb

def to_numbers(word) 
    if(word.size != 10) 
        return "not valid"
    end  
    output = ""
    word.chars.each do |letter|
        output += to_number(letter.downcase).to_s
    end
    return output
end

def to_number(letter) 
    if letter >= "a" && letter <= "c" then return 2 end
    if letter >= "d" && letter <= "f" then return 3 end
    if letter >= "g" && letter <= "i" then return 4 end
    if letter >= "j" && letter <= "l" then return 5 end
    if letter >= "m" && letter <= "o" then return 6 end
    if letter >= "p" && letter <= "s" then return 7 end
    if letter >= "t" && letter <= "v" then return 8 end
    if letter >= "w" && letter <= "z" then return 9 end
end

puts to_numbers("AAAAAAAAAA")