def find_index(phrase: str, letter: str) -> int:
    """
    Find the 'phrase' index at the first occurrence of 'letter' string
    :param phrase: string where the index will be found on
    :param letter: index occurrence
    :return: integer corresponding to 'letter' position
    """

    try:
        return phrase.index(letter)
    except ValueError:
        return -1