MyMethods class so that the static
vowels method returns a string of the vowels of the string parameter. For example, vowels("excercise") would return the string "eeie" because those are the sequence of vowels in the word. Assume vowels are the letters a,e,i,o,u. You can limit your input and output to lower case letters. The vowels method calls a helper method whose parameter are the original string, the starting index where to look for vowels, and the previously found vowels.