def move_consonant_left(letters: list, positions: list) -> list:
    """Given a list of letters, and a list of consonant positions, move the consonant positions to
     the left, merging strings as necessary.
     >>> move_consonant_left(['a', 'b', '', '', 'bra'], [1])
     ['ab', '', '', '', 'bra']"""
    for pos in positions:
        letters[pos - 1] = letters[pos - 1] + letters[pos]
        letters[pos] = ""
    return letters