def _requirements_with_three_elements(requirements):
    """Return true if requirement list looks like ['<', '$ram', '1024']."""
    return (isinstance(requirements, list) and
            len(requirements) == 3 and
            isinstance(requirements[0], str) and
            isinstance(requirements[1], str) and
            isinstance(requirements[2], str) and
            requirements[0] in ['==', '=', '!=', '>=', '<=', '>', '<'] and
            len(requirements[1]) > 1 and requirements[1][0] == '$' and
            len(requirements[2]) > 0)