yellowpager.rb

=begin
Directions

- Write a method that accepts a 10 character string of letters (both uppercase and lowercase)
- if 10 characters in length:
  - define an empty string to a variable (phone_num) - *already done
  - loop through 10 character string (word) - *already done
  - compare letter to telephone mappings and concatenate to the variable (phone_num)
  - return the variable (phone_number)
- else:
  - return false
  
----------------
- You may need to ensure the letter casing of the input string
=end

def yellow_pager(word)
  # concat number characters onto this variable (phone number)
  phone_num = ""

  # ** complete the if expression and statement to meet the condition **
  if word.length
    word.each_char do |letter|
      # ** complete the conditions to map letters to numbers **
      phone_num += letter
    end

    # ** return the mapped phone number **

  else

    # ** return false **

  end
end

# ** call method using the given variable as the argument (you may need to print (puts) the return value) **
word = "Lighthouse"