Translates English word to Pig Latin

Pig Latin

#The main method, it takes a string that is an English word and returns that word in Pig Latin.
#All words have "ay" appended to them in the line just before the return statement. If the word
#begins with a vowel, it is sent to the << "ay" line unmodified.

#If it is exactly three letters long, the second two characters of english_word are made the first
#two of pig_latin_word, then the first letter of english_word is made the third character of 
#pig_latin_word. Then the word is ready to get the << "ay" treatment.
def translate(english_word)
	if is_vowel?(english_word[0])
		pig_latin_word = english_word
	
	elsif english_word.length == 3
		pig_latin_word[0,1] = english_word[1,2]
		pig_latin_word[2] = english_word[0]
	end

	pig_latin_word << "ay"
	return pig_latin_word
end

#Helper method for translate that determines if a character is a vowel or not, returning a boolean
def is_vowel?(string)
  string = string.downcase
  
  if string == "a"
    return true
  elsif string == "e"
    return true
  elsif string == "i"
    return true
  elsif string == "o"
    return true
  elsif string == "u"
    return true
    
  else
    return false
  end
end